Use A2free click here to clear your machine of infections.
The free version runs when you tell it to, however the pay version runs in the background all the time.
Personally I use a compnay called 'Stop-Sign', and have done a few years with no problems. It is a pay site, but at the end of the day, you pay for your Computer , software, and Internet connection.
Is this any different. You only get what you pay for.