I have been working on a clients computer I cannot fix this error:

EXPLORER caused an invalad page fault in module KERNEL32.DLL at 0177:bff87f00

I have tried absoutly everything I could think of. I have already loaded over a couple of times. I tried putting in a diferent hdd and loading windows and it works fine after that but i need to keep everything intact. This even happens in diagnostic mode. Please HELP!