Richard wrote: >ZAP the MBR. (Track ZERO, etc.)>> Hi Richard Thx for your help. If I've done a full reformat, would that not delete the MBR? I have a Paragon Rescue CD which purports to "fix" the MBR. I've just tried that, but no difference. Just to add to what I've already written, I've tried booting from an IDE hard drive with XP installed (off another computer). That brings up the boot options. When I select Safe Mode, the drivers load as far as the usual Mup.sys and then the computer just reboots itself. All fans are working, so it doesn't seem to be an overheating problem. There are no POST beeps so I assume memory is OK. Peter wrote : <<have you tried switching SATA channels for the hard drive?>> Tried that, made no difference. Also tried another cable and power plug. The CDROM is Sata. It's working. Does that tell us that the Sata Controller on the mobo is OK? Or are there different controllers for the hard drive? What next? Don Penlington The NOSPIN Group is now offering Free PC Tech support at our newest website: http://freepctech.com