Tela travando

protected void close(boolean unconditional) {
        System.out.println("[" + this.mainThread.getName() + "] DestroyApp.");
        //new AdViewClose(this, "Advertising");
        System.out.println("[" + this.mainThread.getName() + "] Total of Threads: " + this.mainThread.activeCount());
        Advertising ad =  new Advertising(this, false);
        ad.start();
        if (this.mainThread.activeCount() > 1) {
            synchronized (this) {
                try {
                    System.out.println("[" + this.mainThread.getName() + "] Wait...");
                    this.wait();
                } catch (InterruptedException ex) {
                    ex.printStackTrace();
                    this.notifyDestroyed();
                }
            }
        }
        System.out.println("[" + this.mainThread.getName() + "] Finish app.");
    }

public AdViewClose(MIDlet midlet, String title) {
        super(title);
        System.out.println("[" + THREAD_NAME + "] Star advertising close." );
        System.out.println("[" + THREAD_NAME + "] Midlet: " + midlet);
        Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
        this.midlet = (FrontContainer) midlet;
        System.out.println("[" + THREAD_NAME + "] Print screem close.");
        this.addCommand(new Command("Sair", Command.OK, 1));
        ImageBase imageBase = new ImageBase();
        imageBase.open();
        byte[] image = null;
        try {
            image = imageBase.getImage();
            imageBase.close();
            imageBase.delete();
            this.append(Image.createImage(image, 0, image.length));
            this.setCommandListener(this);
            System.out.println("[" + THREAD_NAME + "] Before display close.");
            Display.getDisplay(this.midlet).setCurrent(this);
            System.out.println("[" + THREAD_NAME + "] After display close.");
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

    public void commandAction(Command c, Displayable d) {
        System.out.println("[" + THREAD_NAME + "] Click close.");
        if (c.getCommandType() == Command.OK) {
            synchronized(this.midlet) {
                this.midlet.notifyAll();
                this.midlet.destroyAppSuper(true);
            }
        }
    }
}