Computer Freeze

[Darkwanderer]

Alright, I have a desktop that i put together myself (About 6 years ago now) When I try to run it standing up, it will go for maybe 45 minutes, but when i try to do anything (like yesterday when i tried to run the net browser) it freezes. So if I lay it down on its side, it runs just fine with no problems. Any ideas as to what could be causing this?

 

[talldude123]

What are the specs of the machine?

HINT: Press the Windows Key and Pause on the keyboard at the same time

 

[Darkwanderer]

I know how to get the specs but here they are:

AMD Athlon XP 1600+
1.4 GHz
768 MB of RAM
Running Windows XP Professional SP2