You need to attach your log file, so I can see if you are e.g. using an unsupported version of Xerces by accident. (The
bug looks to be in Xerces, not NB.) Also please attach your Ant shortcuts; look for *.xml Ant scripts in your userdir's
config/ subdir.

Created attachment 46112 [details]
Ant Shortcuts

Created attachment 46113 [details]
Logfile

Created attachment 46114 [details]
Logfile again (this is the correct one)

In JDK 6.0u2 version of Xerces:

        name = ownerDocument.getNodeName(fNodeIndex);
        int index = name.indexOf(':'); // <-- NPE

Looks to be the same in JDK 7, same in Xerces 2.8.0, and nearly the same in JDK 5. So not some kind of recent bug, I guess.

I do not see any corrupt shortcuts etc.

Leaving open but INCOMPLETE as I have no recollection of anyone getting a similar NPE. If you figure out how to
reproduce, of course say so. (Hint: make a complete copy of your NB installation for archival purposes, then make a copy
of your userdir, and start removing experimental modules, Ant shortcuts, customizations, etc. - anything in your user
dir - and bisect.) Otherwise I will have to close at some point.

I also got an unreproducible:

java.lang.NullPointerException
        at com.sun.org.apache.xerces.internal.dom.DeferredElementNSImpl.synchronizeData(DeferredElementNSImpl.java:145)
        at com.sun.org.apache.xerces.internal.dom.ElementImpl.getAttribute(ElementImpl.java:281)
        at org.apache.tools.ant.module.loader.AntProjectDataEditor.annotateWithProjectName(AntProjectDataEditor.java:92)
        at org.apache.tools.ant.module.loader.AntProjectDataEditor.messageName(AntProjectDataEditor.java:73)
        at org.openide.text.CloneableEditor$2.run(CloneableEditor.java:452)
        at org.openide.util.Mutex.doEvent(Mutex.java:1181)
        at org.openide.util.Mutex.writeAccess(Mutex.java:376)
        at org.openide.text.CloneableEditor.updateName(CloneableEditor.java:447)
        at org.openide.text.CloneableEditorSupport.updateTitles(CloneableEditorSupport.java:2020)
        at org.openide.text.CloneableEditorSupport.notifyModified(CloneableEditorSupport.java:1661)
        at org.apache.tools.ant.module.loader.AntProjectDataEditor.notifyModified(AntProjectDataEditor.java:54)
        at org.openide.text.CloneableEditorSupport.callNotifyModified(CloneableEditorSupport.java:1578)
        at org.openide.text.CloneableEditorSupport$Listener.vetoableChange(CloneableEditorSupport.java:2402)
        at org.netbeans.editor.BaseDocument.notifyModify(BaseDocument.java:1491)

*** Issue 115287 has been marked as a duplicate of this issue. ***

*** Issue 117521 has been marked as a duplicate of this issue. ***

*** Issue 118648 has been marked as a duplicate of this issue. ***

*** Issue 118940 has been marked as a duplicate of this issue. ***

*** Issue 119737 has been marked as a duplicate of this issue. ***

Is the issue still incomplete? It's probably related with shortcuts to ant target in main menu. The exception is thrown
on startup (but not everytime). 

I think it's more general than shortcuts to targets. Do you have some way of reproducing, even only sometimes?

Sorry, I don't have. It works fine now. 

I cannot reproduce this. But under the guess that this is a race condition caused by unsynchronized access to a DOM
tree, I have added code to clone the document before returning it to anyone:

Checking in AntProjectSupport.java;
/shared/data/ccvs/repository/ant/src/org/apache/tools/ant/module/xml/AntProjectSupport.java,v  <--  AntProjectSupport.java
new revision: 1.40; previous revision: 1.39
done