I seem to have a similar problem.
All my shields are working except for the Web Shield. I am running Vista 32 Bit, the latest Avast updates and Internet Explorer 8. IE is incredibly slow and stops responding.
I think the two problems are related but haven't found a way to fix it. I've already spend many frustrating hours trying to resolve this. What am I missing? I should also mention that Mozilla Firefox works just fine!
I just discovered that if I uncheck the "Enable Protected Mode" in the "Securities" tab in the "Internet Properties" in the "Control Panel".... It speeds up IE8 a lot! It is dangerous to do that though, and it doesn't fix the Web Shield issue I have.