Sometimes these interactions between different sites' software can cause problems on some machines and not others and it isn't always possible to reproduce.
Please make sure you have the latest drivers for your graphics card, and have installed the latest Service Pack for your version of Windows, etc.
If you still have problems please open a
Support ticket and give us some more detail about your system and exactly what type of tables you're playing, etc.
All you need to do initially is run with logging enabled and send us the PokerTracker.log and PokerTrackerHUD.log files after your session.
If there is some specific circumstance which causes your problem we will of course try to reproduce it, and fix it where possible.