The avast firewall creates/causes no conflicts with the Windows Firewall. They compliment each other.
If all else fails try a clean install of avast.
Backup your avast settings...GUI>Settings>General> scroll down to "back up settings".
Download and save your preferred version of avast
https://forum.avast.com/index.php?topic=174286.msg1237838#msg1237838Download and save the avast uninstaller
http://files.avast.com/iavs9x/avastclear.exeRun uninstaller>accept the reboot into safe mode.
Reboot.
Install the avast version you selected. (Restore avast settings from above...GUI>Settings>General>scroll down to and click "restore settings")
Reboot and either register or insert license.
avast v2015.10.3.2225 is Win10 compatible. I have it running on my HP Envy (upgraded to Win10 from Win8.1)