Just to be clear, in case someone got confused with several different forum members posting, I am NOT discarding that iYogi's suggestion could be correct for this case, and I am NOT one of those trashing his comments (whether I agree with them or not).
Although we have not enough information, that simple and fast change may, in some cases, solve the OP's problem, without any additional changes or investigations.
Since testing that possibility is fast and simple, the user could report back the result almost immediately. If the problem is solved, we could leave it like that, or even try to narrow down the source of the problem even more (which increases the user's security a little bit more).
OTOH, if the problem is not solved with that change, we just invested a couple of minutes only, and the OP can provide more info for further investigations. Reverting back that one setting is also fast and simple, but should be mentioned explicitly, since most users will leave it even when it didn't help.
Other suggestions, like deleting the firewall rules for example, are also based on many cases and experience. This may or may not solve the problem, but it is much faster and simpler than uninstalling avast, running the removal utility, reinstalling and reconfiguring again (which, BTW, could solve the problem, or maybe not, but it is a PITA for sure).
Now let's wait for the OP's report, as we are all just talking and talking without any real reason nor goal.