jeremym is right. Turn off automatic restart and you will get the blue screen which will give you a clue as to what the problem is. I have had this happen twice with XP Pro, and both times I found the solution by turning off automatic restart. I can not imagine why Micro$oft would default the system to automatically restart on an error! For me, the first time I had the problem it was my video driver for an ATI All-In-Wonder Raedon card. I downloaded the new driver and the problem was solved. On my second system the problem was caused by a DLL file for ON Track virus protection. I looked on their site for a fix but never found one. Now I use Norton instead. On both occasions, the blue screen told me what file was causing the problem. Hope this helps.