I have been using CCleaner on a number of platforms for years. I had been satisfied with its performance and trusted it. Today; however, I downloaded the free upgrade and low and behold along with it came Avast Antivirus. Now maybe I missed the fine print, but it subsequently took me a half hour to uninstall it. I have very disappointed with Piriform/CCleaner for doing this. Fortunately I caught it right away. But what about the potential conflict with other anti virus programa running on your machine. Shame on you Piriform!