Maybe youre internet options have been changed by a piece of malware , go to tools/internet options and then on the security , privacy , and advanced taps , press "default" and apply.

Then try to do an online AV scan again please.

I reset to default settings, but the sites still won't work. I'm running avast! antivirus, ad-aware ad-watch and the free version of Prevx1. This thing is churning out little bits of mal-ware like crazy, I have about 300 things marked by Prevx1.

Does Prevx have the option to make a log? If yes can you post that , or maybe take a screnshot of what it finds?

And can you also post a new hjt log?

Prevx1 seems to be able to monitor one program at a time and make a log, so I'm monitoring smss.exe right now and I'll see what happens. Here's the hjt log.

The Smitrem tool has to be run again to get rid of this one:

O2 - BHO: Nothing - {b0398eca-0bcd-4645-8261-5e9dc70248d0} - I:\WINDOWS\system32\hpC013.tmp

Run smitrem again (in safemode) and then fix the above entry with hjt.
(it will say "file missing" at the end after running Smitrem)

When done , please post the new Smitrem log and a new hjt log.

Well I ran semitem, here's the new hjt log. Prevx shows that malware is still popping up, though.

Can you also post the Smitrem log? And also the results of the monitoring with Prevx?