Mysterious null pointers during Applet.paint(g)

Question

I'm working with the paint function of my applet, which uses double buffering, and I occassionally get an odd null pointer exception, which does not halt its excution, but I believe may be linked to some other unusual behavior regarding components not being painted correctly.
I've been staring at this thing for a while now and I am completely out of ideas.
For debugging purposes, I've expressly checked each object invovled in the painting to ensure that it isn't null, but the exception is still being thrown and java is telling me that the exception is being trown on line numbers that have only a closing brace (see code)
Any help is much appreciated
Here's the code... state is an extension of Container and loading is just a label to display when I'm changing different containers in and out of state
       public void paint(Graphics g) {
          if(offscreen == null) offscreen = createImage(500, 480);
          else {
                  Graphics g1 = offscreen.getGraphics();
                  if(!dontPaint) {
                    if(loading != null && loading.isVisible()) loading.setVisible(false);
                    if(state!=null) state.paint(g1);
               else {
                    if(g1 != null) {
                         g1.setColor(Color.black);
                         g1.fillRect(0, 0, 500, 480);
                    if(!loading.isVisible() && loading!=null) loading.setVisible(true);
                  if(g != null) g.drawImage(offscreen, 0, 0, null);
        }here's an example of the errors:
java.lang.NullPointerException
        at sun.java2d.pipe.DrawImage.copyImage(DrawImage.java:48)
        at sun.java2d.pipe.DrawImage.copyImage(DrawImage.java:715)
        at sun.java2d.pipe.ValidatePipe.copyImage(ValidatePipe.java:147)
        at sun.java2d.SunGraphics2D.drawImage(SunGraphics2D.java:2782)
        at sun.java2d.SunGraphics2D.drawImage(SunGraphics2D.java:2772)
        at StarDart.paint(StarDart.java:113)
        at StarDart.update(StarDart.java:96)
        at sun.awt.RepaintArea.paint(RepaintArea.java:172)
        at sun.awt.windows.WComponentPeer.handleEvent(WComponentPeer.java:260)
        at java.awt.Component.dispatchEventImpl(Component.java:3586)
        at java.awt.Container.dispatchEventImpl(Container.java:1437)
        at java.awt.Component.dispatchEvent(Component.java:3367)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:445)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchTh
read.java:190)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:144)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:130)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:98)

Answer 1

I do have a thread which is always running; I use the Runnable interface. Here is my run() function:
     public void run() {
          while(!stopRunning) {
               for(; sessionInput(); state.handleInput(inBuf));
                       repaint();
                    try {
                               Thread.sleep(100L);
                    } catch(InterruptedException interruptedexception) { System.out.println(interruptedexception); }
          }The for loop manages my networking code. Should I be putting the call to repaint() in a try block?
Does this have something to do with synchronization?