How to produce this case:

Logon to any windows application.
1) start jconsole.
2) connect to any java application (even to jconsole it self).
3) click on memory tab
4) click on GC tab( do gc).
5) click on the Mbean tab
6) in Tree open Memory mbean.
7) operform Gc oprtation from operations
8) click on notifictaions tab
9) click on Subscribe and Unscribe.
10) change to any other tab in Mbean.
It will throw any exception. you should see the following exception in.
After this exception , do unsubscribe/subscribe move to Attributes/ Operations/Info tabs it will throw the same exception on the console.
Exception :
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at javax.swing.JComponent._paintImmediately(JComponent.java:5040)
        at javax.swing.JComponent.paintImmediately(JComponent.java:4843)
        at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:688)
        at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:644)
        at javax.swing.RepaintManager.seqPaintDirtyRegions(RepaintManager.java:6
24)
        at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(System
EventQueueUtilities.java:128)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThre
ad.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.
java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)