What version of PT3?
What were you doing before trying to close?
Was the HUD open on some tables?
What operating system?
If you have logging enabled, please attach the PokerTracker.log and PokerTrackerHUD.log files (zip/compress them first) to the
Support system , and link to this thread.
To stop it, use Task Manager / Processes. Select Pokertracker.exe and 'End' it.