Unless you know what you are doing stay well clear of combofix
I would suggest trying Tdsskiller, Hitman pro and superantispyware. From my experience I suggest only having 1 anti-virus running on your PC (Avast is a good choice but there are loads of others). I also suggest having a number of malware programmes on your PC as I have not found 1 programme that finds everything and you usually have to do a number of scans.
If you want to know 100% that there are no infections on your PC then you can register at Bleeping Computer and post your problem on their forum:
Before posting you should read the sticky threads so you know what to post. These guys are dedicated solely to malware removal. The only downside is it can take a few days to get a response as they are very busy.