Erro ao executar programa

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at javax.swing.ImageIcon.<init>(ImageIcon.java:167) at gui.frameCadastroFuncionarios.initComponents(frameCadastroFuncionarios.java:307) at gui.frameCadastroFuncionarios.<init>(frameCadastroFuncionarios.java:15) at gui.frameTelaPrincipal.<init>(frameTelaPrincipal.java:50) at gui.frameTelaPrincipal$9.run(frameTelaPrincipal.java:513) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209) at java.awt.EventQueue.dispatchEvent(EventQueue.java:597) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Alguem sabe do que se trata esse erro??

desde ja agradeço…
abraço

manda o codigo, talvez fique mais facil

package gui;

import acessoAoBanco.FachadaAcessoCadastro;
import acessoAoBanco.FachadaAcessoCategoria;
import acessoAoBanco.FachadaAcessoFuncionario;
import acessoAoBanco.FachadaAcessoUsuario;
import acessoAoBanco.FachadaAcessoServico;
import acessoAoBanco.acessoMySQL;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DateFormat;
import java.util.Calendar;
import java.util.Date;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.Timer;
import javax.swing.UIDefaults;
import javax.swing.UIManager;
import pojos.Usuario;


public class frameTelaPrincipal extends javax.swing.JFrame implements ActionListener{
    public frameTelaPrincipal() {
        //JPanel x = new JPanel();
        acessoMySQL banco = new acessoMySQL();
        try{
            banco.conectar();
            FachadaAcessoUsuario fachada = new FachadaAcessoUsuario(banco);
            frameLoginUsuario flu = new frameLoginUsuario(fachada, this);
            flu.setVisible(true);

        }catch (Exception e){
            JOptionPane.showMessageDialog (this, "Erro ao conectar com o banco de dados: \n" +
                    e.getMessage(), "Erro de conexao", JOptionPane.ERROR_MESSAGE);

            e.printStackTrace();
            System.exit(0);
        }

        initComponents();
        setSize (800, 600);
        setExtendedState(JFrame.MAXIMIZED_BOTH);

       jlData.setText(DateFormat.getDateInstance().format(new Date()));
        Timer t = new Timer(1000,this);
        t.start();

        funcionario = new frameCadastroFuncionarios(new FachadaAcessoFuncionario(banco));
        servico = new frameCadastroServicos(new FachadaAcessoServico(banco));
        cadastro = new frameCadastroClienteCarro(new FachadaAcessoCadastro(banco));
        novoUsuario = new frameCadastroUsuario (new FachadaAcessoUsuario(banco));
        categ = new  FrameCadastroPorctCateg(new FachadaAcessoCategoria(banco));
    }

    FrameCadastroPorctCateg categ;
    Usuario usuario;
    frameCadastroFuncionarios funcionario;
    frameCadastroServicos servico;
    frameCadastroUsuario novoUsuario;
    frameCadastroClienteCarro cadastro;

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        jPanel3 = new javax.swing.JPanel();
        jLabel22 = new javax.swing.JLabel();
        jTextField6 = new javax.swing.JTextField();
        jLabel23 = new javax.swing.JLabel();
        jTextField7 = new javax.swing.JTextField();
        jButton5 = new javax.swing.JButton();
        jScrollPane2 = new javax.swing.JScrollPane();
        jTable2 = new javax.swing.JTable();
        jSeparator3 = new javax.swing.JSeparator();
        jLabel24 = new javax.swing.JLabel();
        jLabel25 = new javax.swing.JLabel();
        jTextField8 = new javax.swing.JTextField();
        jLabel26 = new javax.swing.JLabel();
        jTextField9 = new javax.swing.JTextField();
        jLabel27 = new javax.swing.JLabel();
        jSeparator5 = new javax.swing.JSeparator();
        jComboBox2 = new javax.swing.JComboBox();
        jScrollPane3 = new javax.swing.JScrollPane();
        jTable3 = new javax.swing.JTable();
        jLabel28 = new javax.swing.JLabel();
        jTextField10 = new javax.swing.JTextField();
        jButton6 = new javax.swing.JButton();
        jButton7 = new javax.swing.JButton();
        jButton8 = new javax.swing.JButton();
        jSeparator7 = new javax.swing.JSeparator();
        jLabel29 = new javax.swing.JLabel();
        jTextField11 = new javax.swing.JTextField();
        jlData = new javax.swing.JLabel();
        jlHora = new javax.swing.JLabel();
        jMenuBar1 = new javax.swing.JMenuBar();
        jMenuOpcoes = new javax.swing.JMenu();
        jmiTelaInicial = new javax.swing.JMenuItem();
        jSeparator8 = new javax.swing.JSeparator();
        jMenuItem3 = new javax.swing.JMenuItem();
        jSeparator10 = new javax.swing.JSeparator();
        jmiSair = new javax.swing.JMenuItem();
        jMenuCadastro = new javax.swing.JMenu();
        jmiCliente = new javax.swing.JMenuItem();
        jSeparator1 = new javax.swing.JSeparator();
        jmiFuncionario = new javax.swing.JMenuItem();
        jSeparator2 = new javax.swing.JSeparator();
        jmiServico = new javax.swing.JMenuItem();
        jSeparator4 = new javax.swing.JSeparator();
        jmiTipoServico = new javax.swing.JMenuItem();
        jSeparator6 = new javax.swing.JSeparator();
        jmiUsuario = new javax.swing.JMenuItem();
        jSeparator9 = new javax.swing.JSeparator();
        jmiPorct = new javax.swing.JMenuItem();
        jMenu2 = new javax.swing.JMenu();
        jMenu3 = new javax.swing.JMenu();
        jMenu4 = new javax.swing.JMenu();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("SISTEMA DE LAVA JATO");
        setCursor(new java.awt.Cursor(java.awt.Cursor.DEFAULT_CURSOR));
        setForeground(java.awt.Color.white);

        jLabel22.setText("Placa do Carro:");

        jLabel23.setText("Nome:");

        jButton5.setText("Localizar");

        jTable2.setModel(new javax.swing.table.DefaultTableModel(
            new Object [][] {
                {null, null, null},
                {null, null, null},
                {null, null, null},
                {null, null, null}
            },
            new String [] {
                "Placa", "Modelo", "Categoria"
            }
        ) {
            Class[] types = new Class [] {
                java.lang.String.class, java.lang.String.class, java.lang.String.class
            };
            boolean[] canEdit = new boolean [] {
                false, false, false
            };

            public Class getColumnClass(int columnIndex) {
                return types [columnIndex];
            }

            public boolean isCellEditable(int rowIndex, int columnIndex) {
                return canEdit [columnIndex];
            }
        });
        jScrollPane2.setViewportView(jTable2);

        jLabel24.setFont(new java.awt.Font("Tahoma", 1, 11));
        jLabel24.setText("Registro");

        jLabel25.setText("Placa:");

        jLabel26.setText("Modelo:");

        jLabel27.setText("Cód. do Serviço:");

        jComboBox2.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Lavagem Simples", "Lavagem Geral", "Lavagem Completa", "Lavagem Interna", "Lavagem de Bancos", "Lavagem de Teto" }));

        jTable3.setModel(new javax.swing.table.DefaultTableModel(
            new Object [][] {
                {null, null},
                {null, null},
                {null, null},
                {null, null}
            },
            new String [] {
                "Tipo de Serviço", "Valor"
            }
        ) {
            boolean[] canEdit = new boolean [] {
                false, false
            };

            public boolean isCellEditable(int rowIndex, int columnIndex) {
                return canEdit [columnIndex];
            }
        });
        jScrollPane3.setViewportView(jTable3);

        jLabel28.setText("Total: R$");

        jButton6.setText("Proximo");

        jButton7.setText("Salvar");

        jButton8.setText("Cancelar");

        jSeparator7.setOrientation(javax.swing.SwingConstants.VERTICAL);

        jLabel29.setText("Pedido Nº:");

        javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
        jPanel3.setLayout(jPanel3Layout);
        jPanel3Layout.setHorizontalGroup(
            jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel3Layout.createSequentialGroup()
                .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel3Layout.createSequentialGroup()
                        .addContainerGap()
                        .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                .addGroup(jPanel3Layout.createSequentialGroup()
                                    .addComponent(jSeparator3, javax.swing.GroupLayout.DEFAULT_SIZE, 702, Short.MAX_VALUE)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED))
                                .addGroup(jPanel3Layout.createSequentialGroup()
                                    .addComponent(jLabel24)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED))
                                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel3Layout.createSequentialGroup()
                                    .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                                        .addGroup(javax.swing.GroupLayout.Alignment.LEADING, jPanel3Layout.createSequentialGroup()
                                            .addComponent(jLabel23)
                                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                            .addComponent(jTextField7, javax.swing.GroupLayout.DEFAULT_SIZE, 483, Short.MAX_VALUE))
                                        .addGroup(javax.swing.GroupLayout.Alignment.LEADING, jPanel3Layout.createSequentialGroup()
                                            .addComponent(jLabel28)
                                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                            .addComponent(jTextField10, javax.swing.GroupLayout.PREFERRED_SIZE, 113, javax.swing.GroupLayout.PREFERRED_SIZE)
                                            .addGap(327, 327, 327))
                                        .addGroup(javax.swing.GroupLayout.Alignment.LEADING, jPanel3Layout.createSequentialGroup()
                                            .addComponent(jLabel25)
                                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                            .addComponent(jTextField8, javax.swing.GroupLayout.PREFERRED_SIZE, 79, javax.swing.GroupLayout.PREFERRED_SIZE)
                                            .addGap(18, 18, 18)
                                            .addComponent(jLabel26)
                                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                            .addComponent(jTextField9, javax.swing.GroupLayout.DEFAULT_SIZE, 340, Short.MAX_VALUE))
                                        .addGroup(javax.swing.GroupLayout.Alignment.LEADING, jPanel3Layout.createSequentialGroup()
                                            .addComponent(jLabel27)
                                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                            .addComponent(jComboBox2, javax.swing.GroupLayout.PREFERRED_SIZE, 130, javax.swing.GroupLayout.PREFERRED_SIZE))
                                        .addGroup(javax.swing.GroupLayout.Alignment.LEADING, jPanel3Layout.createSequentialGroup()
                                            .addComponent(jScrollPane3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                                            .addGap(18, 18, 18))
                                        .addComponent(jSeparator5, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, 518, Short.MAX_VALUE))
                                    .addGap(190, 190, 190))
                                .addGroup(jPanel3Layout.createSequentialGroup()
                                    .addComponent(jLabel22)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                    .addComponent(jTextField6, javax.swing.GroupLayout.PREFERRED_SIZE, 185, javax.swing.GroupLayout.PREFERRED_SIZE)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                    .addComponent(jButton5)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)))
                            .addGroup(jPanel3Layout.createSequentialGroup()
                                .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 518, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)))
                        .addComponent(jSeparator7, javax.swing.GroupLayout.PREFERRED_SIZE, 11, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addComponent(jLabel29)
                            .addComponent(jTextField11, javax.swing.GroupLayout.DEFAULT_SIZE, 133, Short.MAX_VALUE)
                            .addComponent(jlData)
                            .addComponent(jlHora)))
                    .addGroup(jPanel3Layout.createSequentialGroup()
                        .addGap(96, 96, 96)
                        .addComponent(jButton6)
                        .addGap(18, 18, 18)
                        .addComponent(jButton7)
                        .addGap(18, 18, 18)
                        .addComponent(jButton8)))
                .addContainerGap())
        );
        jPanel3Layout.setVerticalGroup(
            jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel3Layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jSeparator7, javax.swing.GroupLayout.PREFERRED_SIZE, 478, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGroup(jPanel3Layout.createSequentialGroup()
                        .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(jPanel3Layout.createSequentialGroup()
                                .addGap(9, 9, 9)
                                .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                                    .addComponent(jLabel22)
                                    .addComponent(jTextField6, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                                    .addComponent(jButton5))
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 92, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addGap(18, 18, 18)
                                .addComponent(jSeparator3, javax.swing.GroupLayout.PREFERRED_SIZE, 10, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(jLabel24)
                                .addGap(5, 5, 5)
                                .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                                    .addComponent(jLabel23)
                                    .addComponent(jTextField7, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                                .addGap(18, 18, 18)
                                .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                                    .addComponent(jLabel25)
                                    .addComponent(jTextField8, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                                    .addComponent(jTextField9, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                                    .addComponent(jLabel26))
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(jSeparator5, javax.swing.GroupLayout.PREFERRED_SIZE, 10, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                                    .addComponent(jLabel27)
                                    .addComponent(jComboBox2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
                            .addGroup(jPanel3Layout.createSequentialGroup()
                                .addComponent(jLabel29)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(jTextField11, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addGap(18, 18, 18)
                                .addComponent(jlData)
                                .addGap(50, 50, 50)
                                .addComponent(jlHora)))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jScrollPane3, javax.swing.GroupLayout.PREFERRED_SIZE, 91, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(18, 18, 18)
                        .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(jLabel28)
                            .addComponent(jTextField10, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGap(18, 18, 18)
                        .addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(jButton6)
                            .addComponent(jButton7)
                            .addComponent(jButton8))))
                .addContainerGap(54, Short.MAX_VALUE))
        );

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );

        jMenuOpcoes.setText("<html><b>Opções ");

        jmiTelaInicial.setText("Tela Inicial");
        jMenuOpcoes.add(jmiTelaInicial);
        jMenuOpcoes.add(jSeparator8);

        jMenuItem3.setText("Busca");
        jMenuOpcoes.add(jMenuItem3);
        jMenuOpcoes.add(jSeparator10);

        jmiSair.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F4, java.awt.event.InputEvent.ALT_MASK));
        jmiSair.setText("Sair");
        jmiSair.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jmiSairActionPerformed(evt);
            }
        });
        jMenuOpcoes.add(jmiSair);

        jMenuBar1.add(jMenuOpcoes);

        jMenuCadastro.setText("<html><b>Cadastro");

        jmiCliente.setText("Clientes");
        jmiCliente.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jmiClienteActionPerformed(evt);
            }
        });
        jMenuCadastro.add(jmiCliente);
        jMenuCadastro.add(jSeparator1);

        jmiFuncionario.setText("Funcionário");
        jmiFuncionario.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jmiFuncionarioActionPerformed(evt);
            }
        });
        jMenuCadastro.add(jmiFuncionario);
        jMenuCadastro.add(jSeparator2);

        jmiServico.setText("Serviço");
        jmiServico.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jmiServicoActionPerformed(evt);
            }
        });
        jMenuCadastro.add(jmiServico);
        jMenuCadastro.add(jSeparator4);

        jmiTipoServico.setText("Tipo de Serviço");
        jMenuCadastro.add(jmiTipoServico);
        jMenuCadastro.add(jSeparator6);

        jmiUsuario.setText("Usuário");
        jmiUsuario.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jmiUsuarioActionPerformed(evt);
            }
        });
        jMenuCadastro.add(jmiUsuario);
        jMenuCadastro.add(jSeparator9);

        jmiPorct.setText("Alterar Porcentagem da categoria");
        jmiPorct.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jmiPorctActionPerformed(evt);
            }
        });
        jMenuCadastro.add(jmiPorct);

        jMenuBar1.add(jMenuCadastro);

        jMenu2.setText("<html><b>Lançamentos");
        jMenuBar1.add(jMenu2);

        jMenu3.setText("<html><b>Consulta");
        jMenuBar1.add(jMenu3);

        jMenu4.setText("<html><b>Relatorios");
        jMenuBar1.add(jMenu4);

        setJMenuBar(jMenuBar1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );

        pack();
    }// </editor-fold>                        
    private void mostrarCadastroPorctCateg(){
        categ.setVisible(true);
        categ.setState(JFrame.NORMAL);
    }


    public void loginValido(Usuario u) {
        usuario = u;
        setVisible(true);
        setTitle("Sistema X: "+u.getNome());
    }

    //Menu cadastro de Funcionários
    private void mostrarCadastroFuncionarios(){
            funcionario.setVisible(true);
            funcionario.setState(JFrame.NORMAL);
    }

    private void jmiFuncionarioActionPerformed(java.awt.event.ActionEvent evt) {                                               
        mostrarCadastroFuncionarios();
    }                                              

    //Menu Sair
    private void jmiSairActionPerformed(java.awt.event.ActionEvent evt) {                                        
        System.exit(0);
    }                                       

    //Menu cadastro de Serviços
    private void mostrarCadastroServico(){
            servico.setVisible(true);
            servico.setState(JFrame.NORMAL);
    }

    private void jmiServicoActionPerformed(java.awt.event.ActionEvent evt) {                                           
        mostrarCadastroServico();
    }                                          

    //Menu cadastro de Clientes
    private void mostraFrameCadastro(){
            cadastro.setVisible(true);
            cadastro.setState(JFrame.NORMAL);
    }

    private void jmiClienteActionPerformed(java.awt.event.ActionEvent evt) {                                           
        mostraFrameCadastro();
    }                                          

    //Menu cadastro de usuarios do sistema
    private void mostraCadastroUsuario(){
            novoUsuario.setVisible(true);
            novoUsuario.setState(JFrame.NORMAL);
    }

    private void jmiUsuarioActionPerformed(java.awt.event.ActionEvent evt) {                                           
        mostraCadastroUsuario();
    }                                          

    private void jmiPorctActionPerformed(java.awt.event.ActionEvent evt) {                                         

        mostrarCadastroPorctCateg();



    }                                        

    public static void main(String args[]) {
        UIDefaults defaults = UIManager.getDefaults();
        defaults.put("ComboBox.disabledForeground", Color.BLACK);
        defaults.put("TextField.inactiveForeground", Color.BLACK);
        defaults.put("TextArea.inactiveForeground", Color.BLACK);

        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new frameTelaPrincipal();
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton5;
    private javax.swing.JButton jButton6;
    private javax.swing.JButton jButton7;
    private javax.swing.JButton jButton8;
    private javax.swing.JComboBox jComboBox2;
    private javax.swing.JLabel jLabel22;
    private javax.swing.JLabel jLabel23;
    private javax.swing.JLabel jLabel24;
    private javax.swing.JLabel jLabel25;
    private javax.swing.JLabel jLabel26;
    private javax.swing.JLabel jLabel27;
    private javax.swing.JLabel jLabel28;
    private javax.swing.JLabel jLabel29;
    private javax.swing.JMenu jMenu2;
    private javax.swing.JMenu jMenu3;
    private javax.swing.JMenu jMenu4;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JMenu jMenuCadastro;
    private javax.swing.JMenuItem jMenuItem3;
    private javax.swing.JMenu jMenuOpcoes;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel3;
    private javax.swing.JScrollPane jScrollPane2;
    private javax.swing.JScrollPane jScrollPane3;
    private javax.swing.JSeparator jSeparator1;
    private javax.swing.JSeparator jSeparator10;
    private javax.swing.JSeparator jSeparator2;
    private javax.swing.JSeparator jSeparator3;
    private javax.swing.JSeparator jSeparator4;
    private javax.swing.JSeparator jSeparator5;
    private javax.swing.JSeparator jSeparator6;
    private javax.swing.JSeparator jSeparator7;
    private javax.swing.JSeparator jSeparator8;
    private javax.swing.JSeparator jSeparator9;
    private javax.swing.JTable jTable2;
    private javax.swing.JTable jTable3;
    private javax.swing.JTextField jTextField10;
    private javax.swing.JTextField jTextField11;
    private javax.swing.JTextField jTextField6;
    private javax.swing.JTextField jTextField7;
    private javax.swing.JTextField jTextField8;
    private javax.swing.JTextField jTextField9;
    private javax.swing.JLabel jlData;
    private javax.swing.JLabel jlHora;
    private javax.swing.JMenuItem jmiCliente;
    private javax.swing.JMenuItem jmiFuncionario;
    private javax.swing.JMenuItem jmiPorct;
    private javax.swing.JMenuItem jmiSair;
    private javax.swing.JMenuItem jmiServico;
    private javax.swing.JMenuItem jmiTelaInicial;
    private javax.swing.JMenuItem jmiTipoServico;
    private javax.swing.JMenuItem jmiUsuario;
    // End of variables declaration                   

    public void actionPerformed(ActionEvent e) {
        Calendar c = Calendar.getInstance();
        int h = c.get(Calendar.HOUR);
        int m = c.get(Calendar.MINUTE);
        int s = c.get(Calendar.SECOND);
        jlHora.setText(h+":"+m+":"+s);
    }

  
}

não esta abrindo nenhum outro frame…

O erro está ocorrendo no frameCadastroFuncionarios, não no frameTelaPrincipal. Você não sabe ler o stack trace?

Enfim, esse erro geralmente ocorre quando você dá um getClass().getResource() num recurso que não existe. No caso, uma imagem. Como diz a documentação do método getResource(), nesses casos, ele retorna null.

Logo em seguida, você tenta atribuir a imagem à um imageIcon. E o imagem icon dispara um IllegalArgumentException se a imagem for nula.

Para resolver o problema, veja a linha 307 do frameCadastroFuncionarios. Provavelmente vai se parecer com isso:

imageIcon = new ImageIcon(getClass().getResource("/imagem/imagem.jpg"));

E confira se o caminho da imagem está correto. Lembre-se que esse caminho é case sensitive.

Muito obrigado pela ajuda!!