Scan, then freeze, then horrific blue screen

Basically, everytime i try to do a scan, my computer locks up, produces that horrific blue screen, then restarts. I also cant do a disk defrag. When the computer freezes a log isnt made so i know which file is causing it. I was recently infected w/ 7 viruses, mostly removed. I tried a boot scan, but that found nothing. I dont think its slowing my computer down, its just annoying not being able to do these maintenance tasks. I was told to obtain a cd to boot off for a scan so windows isnt involved or running. Any way to do this? Thanks.

The boot time scanning would have detected the infections. You could use BART CD, but it’s very costly.
Can you post more info about the blue screen (the error numbers, the problematic driver name, etc.).
Do you use avast? Do you have any other antivirus in this machine? Had in the past?