I have just upgraded from an AMD Duron to a XP 2000+. I havent reinstalled XP or anything, just a straight chip swap. I have installed a coolermaster HCC-001, whilst i wait for my new HHC-001 fan. When i turn on the PC, everything is fine and the CPU temp sits around 40 - 43 degrees. However if i run a 3D Intensive app like 3D mark, then the PC hangs after x time, never in the same place and always when running 3D apps. When XP reboots, i get an message saying there is a possible hardware failure with my GeForce Ti4400, and the driver for this device was unable to complete a write operation. (Detenator 29.42) However this has only happened since i installed the new chip. Eveything else, like the motherboard / memory etc remain the same. Could this be because the CPU is overheating? Even though the fan i am using is certified for this CPU? No warning tone is heard indicating a problem. I have a Gigabyte GA-7VRXP with the latest BIOS update. Or should i reinstall XP from scratch after changing the CPU?