Erro ao iniciar aplicação via Java Web Start

Galera, fiz uma aplicação e armazenei em um servidor com windows 2000 prof. com tomcat 6, utilizo como clientes máquinas com windows 2000 e windows XP, o acesso é via Java web start, sendo que no começo alguns clientes com windows XP funcionavam normalmente, só que agora parou de funcionar, já desliguei o firewall dele e nada, dá a mensagem abaixo, claro tenho o Jre do Java instalado na última versão. Nos clientes com windows 2000 funcionam normalmente, o fogo que a empresa tá migrando para o XP. Alguém sabe como resolver?

java.lang.NullPointerException at com.sun.deploy.util.StringQuoteUtil.digestNextQuote(Unknown Source) at com.sun.deploy.util.StringQuoteUtil.quoteIfNeeded(Unknown Source) at com.sun.deploy.util.StringQuoteUtil.quoteIfNeeded(Unknown Source) at com.sun.deploy.util.StringQuoteUtil.getStringByCommandList(Unknown Source) at com.sun.deploy.util.JVMParameters.getCommandLineArgumentsAsString(Unknown Source) at com.sun.javaws.jnl.DefaultMatchJRE.endTraversal(Unknown Source) at com.sun.javaws.jnl.LaunchSelection.selectJRE(Unknown Source) at com.sun.javaws.jnl.LaunchDesc.selectJRE(Unknown Source) at com.sun.javaws.jnl.LaunchDesc.<init>(Unknown Source) at com.sun.javaws.jnl.XMLFormat.parse(Unknown Source) at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(Unknown Source) at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(Unknown Source) at com.sun.javaws.Main.launchApp(Unknown Source) at com.sun.javaws.Main.continueInSecureThread(Unknown Source) at com.sun.javaws.Main$1.run(Unknown Source) at java.lang.Thread.run(Unknown Source)

Ola,
Vc poderia postar o arquivo jnlp, acho que o problema pode ser algo nele…

Segue o jnlp abaixo

<?xml version="1.0" encoding="utf-8"?> 
<jnlp 
  spec="1.0+" 
  codebase="http://10.11.115.5:8080/contratos"
  href="telacontrato.jnlp"> 

    <information> 
        <title>Sistema Prestadores de Servico - PJ 1.0</title> 
        <vendor>IESA Oleo & Gas S.A.</vendor> 
        <homepage href="http://10.11.115.5:8080/contratos/index.html"/> 
        <description>Sistema Prestadores de Servico - PJ</description> 
        <description kind="short">IESA</description> 
        <icon href="images/logoiesa2.jpg"/>
        
    </information>

    <security>
      <all-permissions/>
    </security>

    <resources> 
        <j2se version="1.5+" href="http://java.sun.com/products/autodl/j2se"/> 
    
        <jar href="contrato.jar"/>

	<jar href="lib/mysql-connector-java-5.0.7-bin.jar"/>

	<jar href="lib/poi-2.5.1-final-20040804.jar"/>

	<property name="bancolog" value="contratos"/>

	<property name="servidorrio" value="10.11.115.5"/>

	<property name="servidormacae" value="10.53.115.5"/>

	<property name="loginlog" value="vhdoliveira"/>

	<property name="senhalog" value="v1j2e3"/>
	
    </resources> 

    <application-desc main-class="controle.ControlePrincipal"/>
</jnlp>