Maybe you could narrow down which shield is causing the problem. Instead of pausing all shields at once, pause them one at a time. For example, go to web shield -> stop -> stop for 10 minutes, and during this 10 minutes, test the behavior. Repeat with each shield (even if you already found one that makes problems, there might be more than one involved), and then report back.
This way, it would narrow down where the problem is.
Just to be sure, could you also delete the firewall rules related to avast and to this Walkman connection (if any)? Then the firewall rules are re-created anew.