Deserialization of Editor generates exception

1.Open IDE
2.Open some java files in editor.
3.Close IDE
4.Open IDE during start up following exception is generated:

Fri Feb 09 13:36:17 GMT+01:00 2001java.lang.NullPointerException: null
java.lang.NullPointerException
	at org.netbeans.modules.java.JavaDataObject.getJavaEditor(JavaDataObject.java:594)
	at org.netbeans.modules.java.JavaDataObject.createCookie(JavaDataObject.java:853)
	at org.openide.nodes.CookieSet$CookieEntry.getCookie(CookieSet.java:258)
	at org.openide.nodes.CookieSet.getCookie(CookieSet.java:84)
	at org.openide.loaders.MultiDataObject.getCookie(MultiDataObject.java:547)
	at
org.openide.text.EditorSupport$EntryEnv.findCloneableOpenSupport(EditorSupport.java:884)
	at
org.openide.windows.CloneableOpenSupport$Listener.support(CloneableOpenSupport.java:254)
	at
org.openide.windows.CloneableOpenSupport$Listener.readResolve(CloneableOpenSupport.java:304)
	at java.lang.reflect.Method.invoke(Native Method)
	at java.io.ObjectStreamClass.invokeMethod(ObjectStreamClass.java:1615)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:393)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:236)
	at
org.openide.windows.CloneableTopComponent.readExternal(CloneableTopComponent.java:165)
	at org.openide.text.CloneableEditor.readExternal(CloneableEditor.java:473)
	at org.openide.text.EditorSupport$Editor.readExternal(EditorSupport.java:528)
	at
org.netbeans.modules.java.JavaEditor$JavaEditorComponent.readExternal(JavaEditor.java:1147)
	at org.openide.windows.TopComponent$Replacer.readObject(TopComponent.java:708)
	at java.lang.reflect.Method.invoke(Native Method)
	at java.io.ObjectInputStream.invokeObjectReader(ObjectInputStream.java:2213)
	at java.io.ObjectInputStream.inputObject(ObjectInputStream.java:1410)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:386)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:236)
	at org.openide.util.io.NbMarshalledObject.get(NbMarshalledObject.java:88)
	at
org.netbeans.core.windows.WindowManagerImpl$TopComponentManager.validateData(WindowManagerImpl.java:1343)
	at
org.netbeans.core.windows.frames.DefaultContainerImpl.validateData(DefaultContainerImpl.java:765)
	at
org.netbeans.core.windows.frames.DefaultContainerImpl.validateData(DefaultContainerImpl.java:738)
	at
org.netbeans.core.windows.frames.MultiTabbedContainerImpl.validateData(MultiTabbedContainerImpl.java:483)
	at org.netbeans.core.windows.ModeImpl.validateData(ModeImpl.java:1175)
	at org.netbeans.core.windows.WorkspaceImpl.validateData(WorkspaceImpl.java:842)
[catch] at
org.netbeans.core.windows.WindowManagerImpl$SerializationReplacer.readResolve(WindowManagerImpl.java:860)
	at java.lang.reflect.Method.invoke(Native Method)
	at java.io.ObjectStreamClass.invokeMethod(ObjectStreamClass.java:1615)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:393)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:236)
	at org.openide.util.io.NbMarshalledObject.get(NbMarshalledObject.java:88)
	at org.openidex.projects.ProjectSupport.updateWindowManager(ProjectSupport.java:310)
	at org.openidex.projects.ProjectSupport.projectOpen(ProjectSupport.java:299)
	at org.netbeans.modules.projects.PSupport.projectOpen(PSupport.java:161)
	at org.netbeans.core.NbProjectOperation.setProject(NbProjectOperation.java:145)
	at
org.netbeans.core.NbProjectOperation.openOrCreateProject(NbProjectOperation.java:192)
	at org.netbeans.core.NonGui.run(NonGui.java:443)
	at org.netbeans.core.Main.run(Main.java:156)
	at org.openide.TopManager.initializeTopManager(TopManager.java:120)
	at org.openide.TopManager.getDefault(TopManager.java:81)
	at org.netbeans.core.Main.main(Main.java:243)
	at org.netbeans.core.TopThreadGroup.run(TopThreadGroup.java:90)
	at java.lang.Thread.run(Thread.java:484)