The uninstaller is bad and got final ERRORS. If you reinstall Avast just later, it becomes much unstable and fails. After uninstalling it normally, you also have to Apply Avast Clean (Google) to fix the unistallation, and get more errors. Download the Avast Offline installer (Google) Chose in Avast Clean to Boot into safe mode. There, apply Avast Clean again, then reinstall Avast in safe mode with the Offline installer (fixes many things), Unistall it normally in safe mode and reboot in normal mode. Then Install Avast with the normal installer (not offline) and you’ll get a STABLE installation. Just in case, go to Menu, Config, Throubleshooting, Repair, to make sure it is fine. Then, you only have to apply the easy change in configuration on my other post (to make Web stable) and everything will go fine with Avast again. 