I think I was lucky, because I had a restore point just before the virus hit and for some strange reason the virus didn't shut down the computer this one time so I was able to use the restore point. I think the virus is gone for now, I checked with TDSSKiller and actually Essential had found it also, but was unable to remove it I guess. It was ZAccess trojan.
It's annoying to know that a virus can hit suddenly without warning. I never download pirate software or run any suspicious software, so it's still a mystery where this trojan came from. Maybe it was just some kind of security hole.