monitor turning off

So yeah, I have a radeon 1300 with a slightly new 22" gateway lcd monitor. ive been playing games (warcraft, oblivion, etc) and have never had a problem. I played them for hours and hours with no problem. Recently, for some strange reason warcraft quits out after playing it for so long (anywhere from 10mins to an hour). When I say "quits out" I mean the monitor turns off and wont turn back on until I restart the PC. The PC will still be running and making the game-play sounds but the monitor just wont turn back on. I can play Americas Army just fine without it turning off. Warcraft and Dungeon Keeper 2 however always results with my monitor turning off.

Anyway, what do I do? I have all new drivers. My PC never did this before until just this week. No big changes or installations recently either. What the heck do I do?

Well, I have never heard of a problem like this, but I recommend checking the temps on your card while you are playing the game before it shuts off the monitor, it's a start.