I recently had to restore my system because of a virus that caused my computer to no longer be able to turn back on. At first there were no problems, and I reinstalled my McAfee program, firefox, and my flash player. But gradually, my internet's been deteriorating in performance. At first it started becoming slower and freezing up, but then it started doing other things, like the bottom of the screen (where the loading bar is) would suddenly go all green when it would start to freeze. Now the problem's gotten much worse. On certain websites, things won't load at all, no matter what I do. Pictures won't show up, on youtube comments get cut off, and on a website where I play games (gaiaonline) the games won't play at all.
I've tried clearing my cache and browsing history, scanning for viruses, uninstalling and reinstalling firefox, none of which has worked. I've tried IE, the problem's the same. I haven't been getting any help on the matter and I'm utterly computer illiterate, so I have no idea what to do.

Thank you in advance!