Don't know why you have a problem with Avast! v6 and PC Tools Firewall v7 as I have both and they play well together on my PC.
I don't have ASC because I don't want any software from that Co.
Specs here: Win XP Home - SP 3 - Avast! free v6 - MBAM PRO. SAS on demand.
The above is just to let you know and hope that someone will come along to help you out.