A trip into the BIOS would be my starting point. Switch on and hold (usually) the F1 key to enter BIOS.
To return to original BIOS settings:
Open the BIOS setup program and select the Exit menu.
Select Load Setup Defaults, press Enter, then select Yes and press Enter to load the original setup.
Select Exit Saving Changes, press Enter, then select Yes and press Enter to save setup changes and exit BIOS.
As this process is not without risk, please wait for a more informed response.
If your friend has a restore disc, that may be needed to effect a repair of XP.