A love job

A good femail friend of mine called me up a week ago and tells me her brother is having issues with his pc and could i call him to sort it out. He told me it just reboots everytime he switches it on randomly. I guide him through system restore and it wont let him, so im guessing he's been watching too much porn.

After putting him in safe mode with netwroking i ask him to instal avast, which it wont let him do, and im starting to scratch my head now, thinking that is is going to be a reformat.

My friend brings round this beaten up packard bell with a measly 1gb of ram and no discs or cd keys. I burn off an iso file of xp and test on my machine and it boots to disk, but for some reason i cannot get it to boot on his. I try vista and it works. Ok this is odd, could it be his dvd writer wont accept rewritable discs? I still dont know.

But i get vista on and 20 hours later i get the updates and service packs on and call a friend who might have some spare ram as working on vista with 1gb of crapp ddr2 is like torture. Luckily he does have a gig spare.. so a tin of chocolates to my m8 later and 2gb in it flies... what a huge difference.

I installed everything a noob could want on his machine and my friend is happy and so is his brother. But for the love of me i cannot work out why it would not boot to xp when it boots on my machine. All i got was press any key for cd / dvd to run then hdd boots in.

Just to put some closure on this any ideas anyone?