Run the regression test javax/swing/JTabbedPane/4499556 and it often fails with the following NPE. This is on Windows XP. Test sometimes comes up and sometimes fails.

Running jtreg with JDK version 1.6.0
Directory "D:/tmp/jtreg" not found: Creating
Directory "D:/tmp/jtreg/scratch" not found: Creating
--------------------------------------------------
TEST: javax\swing\JTabbedPane\4499556\bug4499556.java
JDK under test: (c:/jdk1.6.0)
java version "1.6.0-beta2"
Java(TM) SE Runtime Environment (build 1.6.0-beta2-b77)
Java HotSpot(TM) Client VM (build 1.6.0-beta2-b77, mixed mode)


ACTION: build -- Passed. Compilation successful
REASON: User specified action: run build BasicTester
TIME: 0.812 seconds

ACTION: compile -- Passed. Compilation successful
REASON: .class file out of date or does not exist
TIME: 0.812 seconds
STDOUT:
STDERR:

ACTION: build -- Passed. Compilation successful
REASON: Named class compiled on demand
TIME: 0.75 seconds

ACTION: compile -- Passed. Compilation successful
REASON: .class file out of date or does not exist
TIME: 0.75 seconds
STDOUT:
STDERR:

ACTION: applet -- Failed. Execution failed: Applet thread threw exception: java.lang.NullPointerException
REASON: User specified action: run applet/manual=yesno bug4499556.html
TIME: 1.094 seconds
STDOUT:
STDERR:
java.lang.NullPointerException
at javax.swing.plaf.basic.BasicTabbedPaneUI.rotateInsets(BasicTabbedPaneUI.java:2121)
at javax.swing.plaf.basic.BasicTabbedPaneUI.getTabAreaInsets(BasicTabbedPaneUI.java:1780)
at javax.swing.plaf.basic.BasicTabbedPaneUI.paintContentBorder(BasicTabbedPaneUI.java:1238)
at javax.swing.plaf.basic.BasicTabbedPaneUI.paint(BasicTabbedPaneUI.java:775)
at javax.swing.plaf.metal.MetalTabbedPaneUI.paint(MetalTabbedPaneUI.java:826)
at javax.swing.plaf.metal.MetalTabbedPaneUI.update(MetalTabbedPaneUI.java:707)
at javax.swing.JComponent.paintComponent(JComponent.java:703)
at javax.swing.JComponent.paint(JComponent.java:967)
at javax.swing.JComponent.paintChildren(JComponent.java:804)
at javax.swing.JComponent.paint(JComponent.java:976)
at javax.swing.JComponent.paintChildren(JComponent.java:804)
at javax.swing.JComponent.paint(JComponent.java:976)
at javax.swing.JLayeredPane.paint(JLayeredPane.java:559)
at javax.swing.JComponent.paintChildren(JComponent.java:804)
at javax.swing.JComponent.paintToOffscreen(JComponent.java:5083)
at javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:279)
at javax.swing.RepaintManager.paint(RepaintManager.java:1105)
at javax.swing.JComponent.paint(JComponent.java:953)
at java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:21)
at sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:60)
at sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:97)
at java.awt.Container.paint(Container.java:1727)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:724)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:670)
at javax.swing.RepaintManager.seqPaintDirtyRegions(RepaintManager.java:650)
at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:128)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.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)
STATUS:Failed.Applet thread threw exception: java.lang.NullPointerException

TEST RESULT: Failed. Execution failed: Applet thread threw exception: java.lang.NullPointerException
--------------------------------------------------
Test results: failed: 1
Report written to d:\tmp\jtreg\report.html
Results written to D:\tmp\jtreg
Error: Some tests failed or other problems occurred.