bcr1231 :
mentioned a virus scan since you are only getting issue when online but im pretty positive you will need a bios update through my experiences
So i ran a full system scan via avast, and i got some threats found, managed to clean my system up, no change, black ops 1 still only works in offline mode and freezes on startup sequence in online mode on steam, i havent payed much attention to mw3 but i know im having similar issues with that game aswell. halpppp