7 duplicates so far .... the last GUEST report is from Jirka Sedlacek (jis) NB developer and he has also userdir where
this issue is reproducible.

GUEST: I tried to deactivate Hudson module when I received this exception. It seems to me that this happens with every
module I am trying to deactivate and also the deactivation is not successfull because NetBeans are computing
dependancies forever. 

GUEST: NetBeans standard installation on WinXP SP3 with german language; Java 1.6.0_13-b03 After installing svn support
with "Bundled Subversion Client for Windows", I wanted to uninstall cvs and Mercurial. 

GUEST: Just installed the new IDE 6.7. ... (Right, second installation... The first was the french version... :( )
Tried to remove from the plugin menu :
- Mercial, CSV (keep Subversion).
- Local History
Crashed.
FYI : Did the same in the french version. 

GUEST: Trying to Deactive 'SaaS' and 'SOAP Web Service' plugins 

GUEST: I was trying to Deactivate a plugin from Plugins dialog. This error occurs when I select a plugin and click
Deactivate button. The "Checking for dependencies" dialog will appear, but it will never finish the checking. So I have
to close it without being able to deactivate the plugin. 

GUEST: Used 6.7.1 fcs build with 6.7 userdir, tried to disable some modules (maven, spring, hibernate, software as a
service, subversion) 

Build: NetBeans IDE 6.7 RC3 (Build 200906150201)
VM: Java HotSpot(TM) Client VM, 14.0-b16, Java(TM) SE Runtime Environment, 1.6.0_14-b08
OS: Windows 7, 6.1, x86
User comments: 
STACKTRACE: (first 10 lines)
java.lang.ClassCastException: org.netbeans.modules.autoupdate.services.FeatureUpdateElementImpl cannot be cast to
org.netbeans.modules.autoupdate.services.ModuleUpdateElementImpl
        at
org.netbeans.modules.autoupdate.services.OperationValidator.filterCandidatesToDeactivate(OperationValidator.java:528)
        at
org.netbeans.modules.autoupdate.services.OperationValidator.findRequiredModulesForDeactivate(OperationValidator.java:514)
        at org.netbeans.modules.autoupdate.services.OperationValidator.access$1000(OperationValidator.java:67)
        at
org.netbeans.modules.autoupdate.services.OperationValidator$DisableValidator.getRequiredElementsImpl(OperationValidator.java:421)
        at org.netbeans.modules.autoupdate.services.OperationValidator.getRequiredElements(OperationValidator.java:136)
        at
org.netbeans.modules.autoupdate.services.OperationContainerImpl$OperationInfoImpl.getRequiredElements(OperationContainerImpl.java:339)
        at org.netbeans.api.autoupdate.OperationContainer$OperationInfo.getRequiredElements(OperationContainer.java:373)
        at
org.netbeans.modules.autoupdate.ui.wizards.OperationWizardModel.getRequiredUpdateElements(OperationWizardModel.java:130)
        at org.netbeans.modules.autoupdate.ui.wizards.OperationDescriptionStep$1.run(OperationDescriptionStep.java:180)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:577)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1030)