Shoutbox

Sounds slightly similar to a prob I have had with mine a few times (still don't know the exact reason why).

It will lock up with a screen of bright colours, normally when running a 3D program. Only way to get out of it, is to turn the power off. If I just hit restart, I get a blank monitor. The strange thing about it is, that if I unplug the graphics card, blow all the connections, and plug it back in, everything is fine (sometimes for a week, sometimes for several months).

I would suggest checking all connections are clean, on graphics and memory...