Which version of windows10pro?Did you use the Avast Uninstall Utility / did a clean install the right way ?

Download the Avast Uninstall Utility to your desktop.http://files.avast.com/iavs9x/avastclear.exe
Download the Avast.
http://files.avast.com/iavs9x/avast_free_antivirus_setup.exe

Disconnect from the internet.

Run the Uninstall Utility and accept the reboot to safe mode.
Once complete reboot your system.
Reinstall Avast.