Blue screen with windows vista

Hello,
I am using window vista. . each time i boot up, my system moved to windows , shows a blue screen and then restarts itself.

I have just removed the security tool software from my c drive, bought and ran a spyware doctor with antivirus 2010 which removed all virus related things.

It worked with outlook, internet etc until the computer was re-started, when the blue screen comes up each and every time.

HELP