I am currently having an issue which I thought related to WOW but now it happens all the time. Problem one is the system crashes, screen goes black I get "no signal" on the monitor but all the fans and everything are still running on the system and the system doesn't reboot I have to switch it off to get it started again.
Second problem is whilst playing games and now even when opening the browser the screen goes multi coloured. I can still see the original game or browser I have open but can't read a thing on it.
I am currently running an Athlon 64 x2 5200+ 2.7ghz with 2 gig of ram and a Nvidia geforce 8800gt. I am running Vista 64 Is my system telling me the video card is shot or is there another issue with it. I have updated the drivers to no avail. I thought the system might be overheating but its now running with the side off the case and there is good airflow so I dont think it is overheating. Right now the computer will only run for 5 minutes last crash occurred whilst the control panel screen was open.

Check RAM compatability.

Have you been running this setup for long?
Have you tweaked BIOS settings?

I have had this setup running for a while now. I actually used the ram that the motherboard maker had as compatable and also did a check of the ram last night and it was fine. The system has only been doing this over the past month and last night kept dying every 5 minutes

Download Everest from http://majorgeeks.com/download4181.html and run it to check for temperatures and PSU voltages.
This may be a failing PSU, especially if it is a low wattage one. Have a sniff at the PSU where the air comes out - if is smells at all and the air feels warm this could be the cause.

Is this a sure way to tell? Is there a better diagnostic tool? I have a feeling that my PSU is dying and it seems to 1. smell and 2. be chucking out very warm air.

Sorry to steal focus from the thread. By all means solve the origional problem before mine.

It may not be very sophisticated but it works! Don't let a questionable PSU go bang and wreck your motherboard with a power surge as it goes.