Please help!

[WAM]

I just built a new computer, and sold my old computer to a friend. The old computer works fine lying on its side, but freezes when turned upright.  If it is started upright, it freezes on the black screen after the initial window startup screen.  If it is running and then turned upright, it freezes immediately.

I have reseated the AMD 2200+ CPU and heat sink in the Asus A7V8X motherboard, replaced the thermal paste, installed a fresh copy of Windows XP with SP2, removed and reinstalled the two memory DIMMs, and ASUS GF4 MX 4000 video card. I have tried each of the 512 mb DIMMs separately.  None of these have fixed the problem.

What else can I try?

Has any one else had this problem?

Thanks in advance for your help!

[gussery]

Did you use it on it's side when you had it?

"Back in the day" you never changed the position of a PC once you had used it for a while because the hard drive bearings, platters, etc. would wear in that way.  So if you took a computer that stood up and laid it on it's side or vice versa you would hear the hard drive make noises and fail after a while.  The newer hard drives are not supposed to be subject to this problem but you never know.

[WAM]

The comuter has always been used upright prior to this.  I did replace the hard disk and video card with older modles I had lying around.