happened when debuggin module suite project

java.lang.AssertionError: 
Event: org.openide.explorer.view.VisualizerEvent$Removed
Original event: org.openide.nodes.NodeMemberEvent
current vis. nodes:
Indexes: 0 1 2 3 4 5 6 7 8 
org.openide.nodes.NodeMemberEvent[node=org.netbeans.modules.viewmodel.TreeModelNode@14f46d4[Name=, displayName='AWT-
EventQueue-1' at line breakpoint ProcessPersistence.java : 50], add=false
  0 at 0 = org.netbeans.modules.viewmodel.TreeModelNode@5ed46c[Name=, displayName=ProcessFolderChildern.createNodes:59]
  1 at 1 = org.netbeans.modules.viewmodel.TreeModelNode@1cc1743[Name=, 
displayName=ProcessFolderChildern.createNodes:34]
  2 at 2 = org.netbeans.modules.viewmodel.TreeModelNode@499cf9[Name=, displayName=Hidden Source Calls]
  3 at 3 = org.netbeans.modules.viewmodel.TreeModelNode@b410a[Name=, 
displayName=BasicManagerUI.createBasicManagerDialog:157]
  4 at 4 = org.netbeans.modules.viewmodel.TreeModelNode@db27c2[Name=, 
displayName=ProcessHome._manageClientSideValidations:208]
  5 at 5 = org.netbeans.modules.viewmodel.TreeModelNode@f4caa[Name=, 
displayName=ProcessHome.lnkSubModule2ActionPerformed:1013]
  6 at 6 = org.netbeans.modules.viewmodel.TreeModelNode@723d57[Name=, displayName=ProcessHome.access$400:47]
  7 at 7 = org.netbeans.modules.viewmodel.TreeModelNode@1941f6[Name=, displayName=ProcessHome$10.actionPerformed:513]
  8 at 8 = org.netbeans.modules.viewmodel.TreeModelNode@e0a8d0[Name=, displayName=Hidden Source Calls]
]
curr. snapshot: org.openide.nodes.EntrySupport$Default$DefaultSnapshot
[]
prev. snapshot: java.util.Arrays$ArrayList
[org.netbeans.modules.viewmodel.TreeModelNode@5ed46c[Name=, displayName=ProcessFolderChildern.createNodes:59], 
org.netbeans.modules.viewmodel.TreeModelNode@1cc1743[Name=, displayName=ProcessFolderChildern.createNodes:34], 
org.netbeans.modules.viewmodel.TreeModelNode@499cf9[Name=, displayName=Hidden Source Calls], 
org.netbeans.modules.viewmodel.TreeModelNode@b410a[Name=, displayName=BasicManagerUI.createBasicManagerDialog:157], 
org.netbeans.modules.viewmodel.TreeModelNode@db27c2[Name=, displayName=ProcessHome._manageClientSideValidations:208], 
org.netbeans.modules.viewmodel.TreeModelNode@f4caa[Name=, displayName=ProcessHome.lnkSubModule2ActionPerformed:1013], 
org.netbeans.modules.viewmodel.TreeModelNode@723d57[Name=, displayName=ProcessHome.access$400:47], 
org.netbeans.modules.viewmodel.TreeModelNode@1941f6[Name=, displayName=ProcessHome$10.actionPerformed:513], 
org.netbeans.modules.viewmodel.TreeModelNode@e0a8d0[Name=, displayName=Hidden Source Calls]]
	at org.openide.explorer.view.VisualizerChildren.removed(VisualizerChildren.java:249)
	at org.openide.explorer.view.VisualizerEvent$Removed.run(VisualizerEvent.java:132)
	at org.openide.util.Mutex.readAccess(Mutex.java:362)
	at org.openide.util.Mutex$1R.run(Mutex.java:1301)
	at org.openide.nodes.Children$ProjectManagerDeadlockDetector.execute(Children.java:1801)
	at org.openide.util.Mutex.doWrapperAccess(Mutex.java:1320)
	at org.openide.util.Mutex.readAccess(Mutex.java:351)
[catch] at org.openide.explorer.view.VisualizerNode$QP.run(VisualizerNode.java:709)
	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
	at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
	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)


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Product Version: NetBeans IDE Dev (Build 200811011401)
Java: 1.6.0_10; Java HotSpot(TM) Client VM 11.0-b15
System: Windows XP version 5.1 running on x86; Cp1252; en_US (nb)
Userdir: C:\Documents and Settings\Rajiv Perera\.netbeans\dev