blue screen sometimes

hi, so i got guided in malware removal in ths thread http://forums.majorgeeks.com/showthread.php?t=289620 . no malware detected, only adwares. however, after that, i got lags sometimes, and i got blue screen regularly. i don't know if this is related, but when my laptop was turning on, after the 'welcome' screen, my screen went black for a few seconds, and after that, my wallpaper showed up, and everything else. this has never occured in my laptop. but my concern is about the blue screen. how do i fix it?

 

ok, thanks