Real cute problem…

I have a machine that when I attempt to reinstall XP on, when it reaches the point where XP would check the hard disks, the machine powers off.

Even though XP powers the machine off, I have installed Knoppix and Ubuntu without and problem as a test. They both work flawlessly and detect no hardware issues.

Even after the Linux install and test, XP will power off at the point given above. The machine will be installed only with XP when the issue is figured out.

Does anyone have any idea as to what the problem may be or where I can look? Voltages look fine on a DVM and on an oscilloscope.