Ati Radeon 9800 pro overheating?

Well ive been having a problem in which im playing a game and suddenly it freezes up and the moniter starts flickering with assorted distorted images, Im forced to restart my computer manuel, and when I try to run any game again it will just freeze up and do the same thing. If I shut off my computer for a while and come back Im able to play a game for a while but this problem happens again. I was wondering if this could perhaps be because my video card is overheating?