Graphics issue

I have run into an issue and am wondering if anyone else had this problem. After I run for about 30 minutes with my 5 wow accounts I start seeing big white triangles on the screen and then after a while the Wow windows freeze even though the rest of the computer works fine. The wow clients are actually still running and I can hear stuff, I can even type /logout blindly, but the wow windows are frozen. I can run a full 3dMark from end-to-end without any issues.

Machine specs: Dual core 2.4 GHz CPUS, 4GB memory, Geforce 8800 GTS with 640 MB video mem, 10000 rpm raptor harddrive.

Latest Nvidia driver ( 6.14.11.7813), Directx 9c, Windows XP professional, service pack 3

It sounds like a graphics card issue to me. Do you have another card you could test it out with?

Sounds like your graphics card is artifacting. Sure the cards is given enough power by the PSU? Have you overclocked the card?