This failure happened with Swing's nightly regression tests on windows-i586.
The failing test is: test\\javax\\swing\\JTree\\4654916\\bug4654916.java
Here is the exception:
java.lang.ClassCastException: java.util.WeakHashMap
at java.awt.KeyboardFocusManager.getCurrentKeyboardFocusManager(KeyboardFocusManager.java:151)
at java.awt.KeyboardFocusManager.getCurrentKeyboardFocusManager(KeyboardFocusManager.java:145)
at java.awt.KeyboardFocusManager.getGlobalActiveWindow(KeyboardFocusManager.java:799)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:373)
at java.awt.Component.dispatchEventImpl(Component.java:3785)
at java.awt.Container.dispatchEventImpl(Container.java:1962)
at java.awt.Window.dispatchEventImpl(Window.java:1621)
at java.awt.Component.dispatchEvent(Component.java:3750)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
at java.awt.SentEvent.dispatch(SentEvent.java:50)
at java.awt.DefaultKeyboardFocusManager$DefaultKeyboardFocusManagerSentEvent.dispatch(DefaultKeyboardFocusManager.java:154)
at java.awt.DefaultKeyboardFocusManager.sendMessage(DefaultKeyboardFocusManager.java:180)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:256)
at java.awt.Component.dispatchEventImpl(Component.java:3785)
at java.awt.Container.dispatchEventImpl(Container.java:1962)
at java.awt.Window.dispatchEventImpl(Window.java:1621)
at java.awt.Component.dispatchEvent(Component.java:3750)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
at java.awt.SequencedEvent.dispatch(SequencedEvent.java:93)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:459)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:214)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)