Game Crash: No Signal on Monitor, but CPU working

[McDuffie]

I'm using Radeon 9200 PRO

When I'm playing The Sims 2, the computer hangs randomly, but not frequently.
But when it does, there's a good chance that the monitor would turn black afterwards and display a "No Signal" message.
I turn the monitor off/on again but it still says "No Signal"
I have to restart the CPU so that the monitor would work again.

This also happens while I'm playing Warcraft but once the "No Signal" message appears, the game screen will restore when I turn the monitor on again.

If you need any additional info please ask, I'm not used to reporting problems.
Thank you very much!

EDIT: CPU-Z Info:

Thanks again!