Help with message...

During some games I keep getting a message that will pop up that says "While processing graphics data an exception has occurred you may need to restart the emulator" and it appears as an Access Violation. When it pops up I can just hit enter and keep playing, but it pops up constantly and sometimes I hit enter more than I play the game... What is it and how can I fix it?

Nevermind I figured out the problem. It only happens sometimes, but when it does happen it's because the game is in window mode. Once I switch it to full screen it never does it again. Problem solved!!