Asus GeForce4 Ti4400 Problem, please help

[Wynner3]

Today my friends computer was doing ok and all of a sudden everything turned yellow. We spent about an hour trying to figure out what it was and finally found out that it was the video card. It hasn't had any problems until today. Does anybody know why it all of a sudden did this? He uses WinXP Home, has a P4 2.5Ghz system, 512 DDR something memory, SB Audigy, etc... No problems and all of a sudden, yellow.