I think the card is defective but never returned it because I got it to run stably by reducing the AGP bus speed from 66 to 50 MHz. It's in an Asus NF2/Athlon XP box right now and when it's doing well I don't have to reboot for weeks. Have you tried running your card under 66 MHz?
Right after I posted this I thought, what the hell, I had some free ATI tech support coming on their toll free number because I had just bought the AIW 800XT, so I called them and hooked up with tech in a few minutes. He told me to RMA it.... the cards on the way. It gave me no problems until last May so I don't think it is a bad card per se.
My current 6600GT is stable as a rock! Ever since Ati started pushing their chipset business their video cards have really suffered. Pretty similar to nVidia when they first started to break into the chipset biz. I hope Ati can turn their company around like nVidia has over the past year. @:)>
