TSGL: Can you HELP???

[Baracouder]

Hello all, a friend of mine had a problem after problem with his pc, if 
it wasnt one thing it was another, ye get the picture.
I said give me your winxp pro disk and I will reinstall a fresh 
installation as he had nothing he wanted backed up. I took his hard 
drive and hooked it up in my pc, all going well, installed xp and 
started installing a few progs like ccleaner, erunt and regseeker. 
Everything was fine until I hooked back up to his pc (it booted fine in 
my pc). It would hang on startup and if I selected "Last known config" 
it hung, if I selected "safe mode" it hung at "mup.sys" every time. I 
have tried reseaeting the memory, nothing. I tried booting from the cd 
in his own machine but when it came to "press F8 to continue" it wouldnt 
accept but it would when I pressed "Esc to quit".

Please help resolve my dilemma

Many thanks..