This Bugzilla instance is a read-only archive of historic NetBeans bug reports. To report a bug in NetBeans please follow the project's instructions for reporting issues.
It seems to be random. See attached thread dump.
Created attachment 110575 [details] Thread dump with a deadlock
Created attachment 110576 [details] Application snapshot from VisualVM
*** This bug has been marked as a duplicate of bug 201775 ***