Monitor shutting off during gameplay of Sims 2

My problem with Sims 2 is that when I am playing it I can only play it for about 10 to 20 minutes when the monitor will shut off. The game is still running and the sound is still playing but the monitor will shut off saying it's power saving as if I've left the monitor sit for 2 hours. I have checked the power management of the screen saver and that's not the problem. Do you think I need to update my graphics card? And if I do where do I go?

Try turning off all Power Saving options including Screen Savers and see if the problem persists.

Well I tried the power management with the screen savers and what not. That didn't help. So now what?

Do you have the problem outside of this game?

No just when I play Sims 2. I will start playing and in the middle of gameplay the monitor will shut off and I cannot go back to the desktop unless I restart the monitor completely. The sounds will still play as if the game is running. But the monitor will shut off.