Problems with Connect3D Radeon 9550

I have the most up to date drivers installed on my pc for every component and program.

I run an Intel P4 2.4 Ghz Processor
Have 1 gig of DDR Memory
Sound blaster Audigy

(and the problem)

Connect 3D Ati Radeon 9550 256MB video card

The problem comes whenever I go to play any games on the pc.

It loads up into the game but when you go to start a new game or continue one, the monitor looses the signal and reports that it has dropped below 30Mhz.

I can't get into window with this blank screen or anything but the pc still runs as normal.

When I reboot the machine it works fine. I can do everything except play games on it.

All the games have the most up to date patches on. I have even tried the games without the patches.

Any ideas how to combat this?