Monitor flashing off and on durring play.

[Tzarlix]

I'm just bought a Princeton Graphics Senergy 714 monitor. It works absolutly fine with my nVidia GeForce 3 card with every other program and game I have except for Dawn Of War. When I start a game it runs and I can click around and run things but then suddenly the screen will flash black and come back in a second or so. This happens quite a bit. Any clues what I can do to stop it?

Thanks!