I wish I'd known about the extended support for version 7.5 earlier! I deleted the crawling AVG 8 and downloaded the paid version of Kaspersky 7.0, which had glowing reviews. The first thing it did was tell me that my (also paid-for) version of Zone Alarm Anti-spyware was incompatible and had to be removed. This included the latest version of their firewall. I tried to load an earlier version of the firewall but it repeatedly failed because of a corrupted ZA file from their download section (as I found out from the experiences of others on a web search) Downloaded ZA version 6-something from Oldapps and now everything seems fine.
A shame about AVG 8 because I've been using Grisoft products for several years without cause for complaint. No point in griping too much because it's always been free.