My computer restarts often when my Graphic card is used more then in
windows mode (aka in games). but it sometimes restarts when it's in
windows mode.. only with firefox/winamp opened.
Try a good cleaning. Unplug the power cord from your PC. Remove the sides of your case. Using air blow everything off.
CPU, heatsink & PSU from both sides /outside to in & inside to out. Than remove the video card and clean its slot. Than clean the card its self. It would not hurt to remove your memory and clean their slots, reseat. Update windows!
If your broblem stops your done. If is hasn't doenload the latest driver from ATI: http://ati.amd.com/support/drivers/xp/radeon-prer300-xp.html Remove old drivers from control panel before installing new drivers. If your old drivers fail to remove. Download & run ATI's uninstall utility: