If I may, I think that the real help on "cleaning" or "removal" is more a manual, knowledge, intelligence issue, more than about a specific software. Specially, with so many new malware and different malware types every day.
I would say that when avast (or any other security tool for that matter) shows you some sign of a suspect, the user needs to get help from people (users) that REALLY know what they are doing. In that sense, you will find here in the forum other users that will help you step by step, specially is you are already using avast (as forum members here will take the correct info from avast so to give you better steps or specific tools for you to run).
Reading the "Viruses and Worms" subforum may give you a partial (but helpful) idea, with more difficult cases and others not so much.