+2 I have no issue at all with OPFW with Avast 9 on W8
as DvaidR said you don’t need OPFW with Web Control because Avast already have web shields, when you install a software always set OPFW to learning mode first for 1 day (24hrs) before you start that way you won’t get any confliction after 24hrs OPFW reset it back to Rules Wizards.