I have a ticket in on this since 8/24/2011
Ticket number: 42991072
It happens in 16.3, and 16.5 but have not seen it 16.6, yet.
Here's how I fix it (Instructions from cadence support):
to task manager and see if any cadence process (capture.exe, cdsMsgServer.exe,
cdsNameServer.exe) is running. If so please kill it manually.
to Start > Type regedit. This opens registry editor
c. Now locate and delete 16.3 key
located at HKEY_CURRENT_USER\Software\OrCAD\CaptureWorkSpace
Once this is done the problem will only come back after I do a hotfix.
Hopely Cadence will figure this out.