No joy.....
Have you tried turning the Web Shield off since you last re-installed, if not try that again to make sure it is indeed same problem.
Also, since this is now Avast Internet Security you have installed, does the firewall have a rule for Fx established yet?
btw, you have 20 posts now, if you wouldn't mind modifying your profile to include basic system info (like mine, but without the....colorful parts at the end), it can help the forum members help you.