If you do a reinstall (uninstall then reinstall - not repair), make sure you are doing a clean install and clean leftovers by Avast before installing the new version.
From my experience, I don't have any bad leftovers by Avast so I think you are alright.
Good Luck!

Just a note, if PING *Avast Server* fails on your system, most likely is that reinstalling the application will not help. Seems more like an Internet connection problem to me.