A few days ago, my computer would freeze up and red lines would appear across the screen, making me have to reboot. Thinking it could be an overheating issue, I cleaned out some dust from my video card fan and heat sink, and the problem seemingly went away. Then today, I had the same thing happen, but this time the computer would not start up again, and I get lines like http://farm6.static.flickr.com/5284/5213363397_af5ded94... this. If I try to start Windows normally, the computer just restarts after going through all the monitor's display modes. I can only start up in safe mode, and I still have lines in Windows. Any idea what the problem could be? Thank you.
Windows 7 x64
GeForce 8800 GTS 512 - latest drivers
Core 2 Duo 2.6ghz
4mb Corsair XMS DDR2 RAM
ASUS P5b-Plus mobo