Blue Screen Error

Hi all,
This is very critical issue that one of microsoft's software has,im not sure
if anybody has encontered this same problem. "Windows Defender" is a big
problem in Vista. I downloaded Vista and it worked fine the aero glass and
everything, but after some time it started popping blue screens specially
this error message in particulatr "0x0000007F: UNEXPECTED_KERNEL_MODE_TRAP"
there is nothin u can do to fix this problem, there were a few more types of
blue screen errors that might pop up; good trouble shooting techniques can be
found on this website http://www.aumha.org/win5/kbestop.php anyways,i had
to reinstall xp pro and i was installing every software one by one very
slowly, then at last installed windows defender and when it was doing the
system scan the blue screen popped up again. I think I made my point, Iff
anybody knows how to delete or disable 'Defender' in Vista tha would be
great.I know nobody else had this problem, I searched every where.
Thanks