I use CCleaner and keep it updated. With the last few updates, I discovered at the bottom of the setup screen (where you click to install the update) an option to install Avast Free Antivirus application. The first two times I found this option, I unticked the "Yes".....as I did not want Avast Free Antivirus on my computer. The third time I missed that step and I ended up with the application installed on my computer. I had to download the Avast Free Antivirus uninstaller, restart my computer in safe mode to perform the uninstall.
Thus this post is to alert other CCleaner users to pay attention to this new feature (it was for me) when you install the update.
Note: Sharing this discovery is not to imply that I do not recommend the application.