Happened on NetBeans start. Here is a copu if ide.log file:
-------------------------------------------------------------------------------
>Log Session: Monday, January 29, 2001 10:49:46 AM PST
>System Info:
  Product Version          = NetBeans IDE 3.1 (Build 34)
  IDE Versioning           = IDE/1 spec=1.1.2 impl=Build 34
  Operating System         = Windows NT Version 4.0 Running on x86
  Java Version             = 1.3.0
  Java VM Version          = Java HotSpot(TM) Client VM 1.3.0-C
  Java Vendor              = Sun Microsystems Inc.
  Java Vendor URL          = http://java.sun.com/
  Java Home                = D:\JBUILD~2\jdk1.3\jre
  Java Class Version       = 47.0
  System Locale            = en_US
  JIT                      = unknown or not used
  Home Dir                 = C:\WINNT\Profiles\elena
  Current Directory        = d:\netbeans
  IDE Home                 = D:\netbeans
  IDE User Home            = D:\netbeans
  System Directory         = D:\netbeans\system
  CLASSPATH                = D:\netbeans\lib\patches\openide-
compat.jar;D:\netbeans\lib\locale\core_ja.jar;D:\netbeans\lib\locale\openide_ja.
jar;D:\netbeans\lib\core.jar;D:\netbeans\lib\openide.jar;D:\netbeans\lib\updater
.jar;D:\netbeans\lib\ext\locale\openidex_ja.jar;D:\netbeans\lib\ext\locale\vcsco
re_ja.jar;D:\netbeans\lib\ext\AbsoluteLayout.jar;D:\netbeans\lib\ext\djava.jar;D
:\netbeans\lib\ext\jaxp.jar;D:\netbeans\lib\ext\jh.jar;D:\netbeans\lib\ext\jpyth
on.jar;D:\netbeans\lib\ext\openidex.jar;D:\netbeans\lib\ext\parser.jar;D:\netbea
ns\lib\ext\regexp.jar;D:\netbeans\lib\ext\servlet.jar;D:\netbeans\lib\ext\vcscor
e.jar;D:\JBUILD~2\jdk1.3\lib\dt.jar;D:\JBUILD~2\jdk1.3\lib\tools.jar
-------------------------------------------------------------------------------
[INFO] Loaded modules: org.apache.tools.ant.module (1.2/34);
org.netbeans.modules.clazz/1 (1.4/34); org.netbeans.modules.html/1 (1.4/34);
org.netbeans.modules.httpserver/1 (1.4/34); org.netbeans.modules.icebrowser/1
(1.4/34); org.netbeans.modules.image/1 (1.4/34);
org.netbeans.modules.properties/1 (1.4/34); org.netbeans.modules.i18n/1
(1.4/34); org.netbeans.modules.text/1 (1.4/34);
org.netbeans.modules.usersguide/1 (1.4/34); org.openidex.util/1 (1.4/34);
org.netbeans.modules.autoupdate/1 (1.4/34);
org.netbeans.modules.debugger.core/1 (1.1.6/34); org.netbeans.modules.applet/1
(1.4/34); org.netbeans.modules.debugger.debug/1 (1.6/34);
org.netbeans.modules.debugger.jpda/1 (1.6/34); org.netbeans.modules.editor/1
(1.5/34); org.netbeans.modules.jarpackager/1 (1.4/34);
org.netbeans.modules.java/1 (1.4/34); org.netbeans.modules.beans/1 (1.4/34);
org.netbeans.modules.form/1 (1.4/34); org.netbeans.modules.javadoc/1 (1.4/34);
org.netbeans.modules.objectbrowser/1 (1.4/34); org.netbeans.modules.projects/1
(1.4/34); org.netbeans.modules.scripting/1 (1.1/001);
org.netbeans.modules.utilities/1 (1.4/34); org.netbeans.modules.vcs.cmdline/1
(1.3.1/1160); org.netbeans.modules.web.core/1 (1.1.4/34);
org.netbeans.modules.vcs.advanced/1 (1.3.1/1160)
*********** Exception occurred ************
Mon Jan 29 10:49:57 PST 2001java.util.MissingResourceException: null
java.util.MissingResourceException: cannot find resource for
org/netbeans/modules/vcs/advanced/docs/vcs.hs
	at org.openide.util.NbBundle.getLocalizedFile(NbBundle.java:236)
	at org.openide.modules.ModuleDescription.getDescription
(ModuleDescription.java:443)
	at org.netbeans.core.ModuleItem.getRealHelpSet(ModuleItem.java:270)
	at org.netbeans.core.ModuleItem.restoreDefault(ModuleItem.java:329)
	at org.netbeans.core.ModuleInstaller.initialize
(ModuleInstaller.java:190)
	at org.netbeans.core.NonGui.run(NonGui.java:431)
	at org.netbeans.core.Main.run(Main.java:153)
	at org.openide.TopManager.initializeTopManager(TopManager.java:120)
	at org.openide.TopManager.getDefault(TopManager.java:81)
	at org.netbeans.core.Main.main(Main.java:238)
	at org.netbeans.core.TopThreadGroup.run(TopThreadGroup.java:90)
	at java.lang.Thread.run(Thread.java:484)
java.io.IOException: Could not connect to URL
nbrescurrloc:/org/netbeans/modules/vcs/advanced/docs/vcs.hs; no such resource
was found.
	at org.openide.execution.NbResourceStreamHandler$Connection.connect
(NbResourceStreamHandler.java:114)
	at org.openide.modules.ModuleDescription.getDescription
(ModuleDescription.java:436)
	at org.netbeans.core.ModuleItem.getRealHelpSet(ModuleItem.java:270)
	at org.netbeans.core.ModuleItem.restoreDefault(ModuleItem.java:329)
	at org.netbeans.core.ModuleInstaller.initialize
(ModuleInstaller.java:190)
	at org.netbeans.core.NonGui.run(NonGui.java:431)
	at org.netbeans.core.Main.run(Main.java:153)
	at org.openide.TopManager.initializeTopManager(TopManager.java:120)
	at org.openide.TopManager.getDefault(TopManager.java:81)
	at org.netbeans.core.Main.main(Main.java:238)
	at org.netbeans.core.TopThreadGroup.run(TopThreadGroup.java:90)
	at java.lang.Thread.run(Thread.java:484)
java.lang.IllegalStateException
	at org.openide.modules.ModuleDescription.getDescription
(ModuleDescription.java:445)
[catch] at org.netbeans.core.ModuleItem.getRealHelpSet(ModuleItem.java:270)
	at org.netbeans.core.ModuleItem.restoreDefault(ModuleItem.java:329)
	at org.netbeans.core.ModuleInstaller.initialize
(ModuleInstaller.java:190)
	at org.netbeans.core.NonGui.run(NonGui.java:431)
	at org.netbeans.core.Main.run(Main.java:153)
	at org.openide.TopManager.initializeTopManager(TopManager.java:120)
	at org.openide.TopManager.getDefault(TopManager.java:81)
	at org.netbeans.core.Main.main(Main.java:238)
	at org.netbeans.core.TopThreadGroup.run(TopThreadGroup.java:90)
	at java.lang.Thread.run(Thread.java:484)
path="" :jsp: init
*********** Exception occurred ************
Mon Jan 29 10:50:30 PST 2001java.lang.ArrayIndexOutOfBoundsException: No such
child: 1
java.lang.ArrayIndexOutOfBoundsException: No such child: 1
	at java.awt.Container.getComponent(Container.java:170)
	at javax.swing.JComponent.rectangleIsObscured(JComponent.java:3615)
	at javax.swing.JComponent.paint(JComponent.java:737)
	at javax.swing.JComponent.paintWithBuffer(JComponent.java:4393)
	at javax.swing.JComponent._paintImmediately(JComponent.java:4336)
	at javax.swing.JComponent.paintImmediately(JComponent.java:4187)
	at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:370)
	at org.netbeans.core.windows.PinRepaintRM.paintDirtyRegions
(PinRepaintRM.java:75)
	at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run
(SystemEventQueueUtilities.java:205)
	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:154)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:317)
[catch] at java.awt.EventDispatchThread.pumpOneEvent
(EventDispatchThread.java:103)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:84)