Have had a similiar problem once, when building a PC. The problem was caused by the processor not being fully/properly seated on the connection point. However I was using an AMD Athlon slot a (cartridge processor) at the time. You have not said what kind of processor your friend has. The other thing being - & I dont know, I could be way off the mark here - but have you tried booting to something else, such as a bootable DOS floppy, just to rule out some weird glitch in the OS, by this I mean don't try to start XP, try to start something else, anything else.