thnx for the replies, @ahnilated: I don't really know. I mean I know how to, but the problem is that I don't know when it will decide to hang. By the time it does freeze on me, the only thing that is responsive is the Hard Reset.
I would just go into safe mode, delete the current video driver and install a different one. Just to test it out to make sure there isn't something wrong with it.
It sounds almost hardware related if it happens sometimes and then not others.