trouble installing windows 7

upgraded my pals system to 7 earlier but i got the BSOD with the machine check exception, i then started again and again and kept getting the same prob

took the machine up2 pc world and they ran a 10 min diagnostic and said all hardware was working fine but the cpu fan was dirty so splashed out a tenner and got some air and gave it a blow out

started up the install again and it came up with the same BSOD

then went back to installing XP and it came up with the same

ive also took out one of the ram sticks and tried it but it kept doing the same

any clues?

"machine check exception" is not much to go on.

CPUs provide a mechanism to detect and to report hardware-related problems such as memory parity errors and cache errors. To signal a hardware error, the processor signals the detection of a machine check error by generating a machine check exception (Interrupt 18). Windows simply reports the fact that the error occurred and displays parameters that you can use to decode the exception.

What is the exact error message?

its coming up with a STOP message with a long line of `0`s and a few numbers, i never wrote the numbers down:o

i`ll post them when i go back up

That particular Stop error is bad news, it usually means serious hardware problems. First of all go into the BIOS Setup and choose "Load optimised defaults" and see if that helps.