Thanks for the replies. Its intel celeron D, microstar ms 7211 motherboard, with 1gb ram (brand new just installed half an hour ago), with 80 gb western digital hard drive. We've reformatted the hard drive, thinking that might be the problem, and now can't get through the install of the xp on the hard drive before it restarts again, just like before. We've left the screen open to the "health" screen, and it doesn't appear to ever go above the max temp before restart level. The fan on the cpu is working, the side of the cpu box is open, the fan on the back of the computer is going, yet it keeps restarting. We've reset the cmos by removing the battery and changing the jumpers, then changing them back. 'We are just at a total loss at the moment.