laptop will not boot when at home

have you gone home with him to see if maybe he's just not that computer literate?  this is really odd...are you serious?

I think this is more of a case of the user as opposed to the cpu...if it works for everyone else, then there's a problem...i would suggest that you go home with him one day to check it out...maybe he's pulling your leg...i would have said maybe he was on another power voltage, but if even with the battery, he says its not booting and yet everyone else who takes it home, it works, that doesn't make sense...

the best test i can tell you is to give him another laptop and see what happens...

I am not kidding.  I have not gone to his home to see what is going on. He knows how to use it, he uses it at his office.  To make things wierder, he has another laptop at home that works.

He says it does not boot, not sure if it even posts?  I will find out.

Update:
The laptop POSTS, starts booting, gets to XP splash screen, then blue screens.  

Error he gets: Stop: 0x0000000A (0xF895A100, 0x00000002, 0x00000001, 0x804D9BBA

This machine has all service packs.  We are thinking it may be his wireless card.  I will check for updated drivers for the card.

here's something...tell him to try a neighbors house to see so you can single it down just to his house and not the neighborhood...have to think more on this, but at least you can start eliminating some theories...

could be a memory or HDD fault, and it's just a coincidence that it produce all the times at work, or in transportation the laptop is chocked. try in safe mode, and further with a live cd linux (or with wubi).