Thanks for your report Kantjer. I'm still testing Ad Munch, and currently the easiest solution (if I omit your beta 4.7 suggestion) is to setup proxy in Internet Explorer / Firefox to WebShield - server: localhost, port: 12080. With this setup Ad-Munch works correctly with the browser and WebShield and I can not observe any problems with page loading. And this way no avast4.ini changes are needed.
Cheers Lukas.