Do your scans in windows safe mode and disconnect from the internet so plug out your ethernet cable.
And if you get the blue screen again enter it's stop message here, or look it up at the internet. If you don't come up with something, post the stop message and your full hardware list.
I while back I used to get stop messages about something with the memory, seems the problem was with an intern modem that caused the random crashes, and I even didn't use the modem. Took me a while to figure that out.