i have just overviewed avast on-access scanners and Network Shield is on 0 for scan count,been like that for ages,what does Network Shield actually do? When i click custom and theres " last attacks " , sounds like a firewall, is it a firewall? ???
Network Shield provider protects your computer from Internet worm attacks. It works similarly to a firewall, even though it does not fully substitutes it. The Network Shield does not require any user interaction.
You will only see the 0 increase if you had an attack and it is reset to 0 every reboot, the same is true of the Last attacks which list the last 10, there will be nothing there if the count is 0.
Also, I think your firewall (if configured properly) would stop most worm attacks before avast needed to. I still keep Network Shield running as an important backup.