[ BUILD # : 200807170007 ]
[ JDK VERSION : 1.6.0_06 ]

I've done
1. create JFrameForm
2. setLayout -> borderlayout
3. Add JPanel
4. Right-click the jPanel in 'Inspector' window
5. I've got an error as below.

When I right-click the jPanel at the Design window, no exception was
occurred. Just only when I right-click the item in 'Inspector'
window.


Exception Error===================================

java.lang.IllegalStateException: getNodes(true) called while holding
the Children.MUTEX
	at
org.openide.loaders.FolderChildren.waitOptimalResult(FolderChildren.ja
va:232)
	at
org.openide.loaders.FolderChildren.getNodes(FolderChildren.java:212)
	at
org.netbeans.modules.form.palette.PaletteUtils.getCategoryNodes(Palett
eUtils.java:436)
	at
org.netbeans.modules.form.palette.PaletteUtils.getCategoryNodes(Palett
eUtils.java:412)
	at
org.netbeans.modules.form.palette.PaletteMenuView.getSubNodes(PaletteM
enuView.java:134)
	at
org.netbeans.modules.form.palette.PaletteMenuView.<init>(PaletteMenuVi
ew.java:82)
	at
org.netbeans.modules.form.palette.PaletteMenuView.<init>(PaletteMenuVi
ew.java:74)
	at
org.netbeans.modules.form.palette.PaletteMenuView.<init>(PaletteMenuVi
ew.java:70)
	at
org.netbeans.modules.form.actions.AddAction.getPopupPresenter(AddActio
n.java:103)
	at org.openide.util.Utilities.actionsToPopup(Utilities.java:2657)
	at org.openide.util.Utilities.actionsToPopup(Utilities.java:2737)
	at org.openide.explorer.view.TreeView.createPopup(TreeView.java:909)
	at
org.openide.explorer.view.TreeView$PopupAdapter.showPopup(TreeView.jav
a:1379)
	at
org.openide.awt.MouseUtils$PopupMouseAdapter.maybePopup(MouseUtils.jav
a:182)
	at
org.openide.awt.MouseUtils$PopupMouseAdapter.mouseReleased(MouseUtils.
java:177)
	at
java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:27
3)
	at
java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:27
2)
	at
java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:27
2)
	at java.awt.Component.processMouseEvent(Component.java:6041)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
	at java.awt.Component.processEvent(Component.java:5806)
	at java.awt.Container.processEvent(Container.java:2058)
	at
org.openide.explorer.view.TreeView$ExplorerTree.doProcessEvent(TreeVie
w.java:1628)
	at
org.openide.explorer.view.TreeView$ExplorerTree.access$1900(TreeView.j
ava:1484)
	at
org.openide.explorer.view.TreeView$ExplorerTree$GuardedActions.run(Tre
eView.java:1981)
	at org.openide.util.Mutex.readAccess(Mutex.java:285)
	at
org.openide.explorer.view.TreeView$ExplorerTree$GuardedActions.<init>(
TreeView.java:1963)
	at
org.openide.explorer.view.TreeView$ExplorerTree.processEvent(TreeView.
java:1623)
	at java.awt.Component.dispatchEventImpl(Component.java:4413)
	at java.awt.Container.dispatchEventImpl(Container.java:2116)
	at java.awt.Component.dispatchEvent(Component.java:4243)
	at
java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)

	at
java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
	at java.awt.Container.dispatchEventImpl(Container.java:2102)
	at java.awt.Window.dispatchEventImpl(Window.java:2440)
	at java.awt.Component.dispatchEvent(Component.java:4243)
[catch] at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
	at
org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.ja
va:104)
	at
java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThrea
d.java:273)
	at
java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.j
ava:183)
	at
java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThrea
d.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)