When I activate the windows vista firewall no url in the internet can be reached.
Hint: The 7.1 free version doesn´t comprise a firewall.
First there isn’t an avast 7.1 version, it is avast 7.0.1466.
Second the avast free version doesn’t have a firewall so there is no conflict with any firewall as such.
Do you have outbound protection enabled in the Vista Firewall ?
Have (or did) you another Anti-Virus installed in this system, if so what was it and how did you get rid of it ?
What other security software (anti-spyware, firewall, etc.) do you have installed ?
Found out the solution myself. Timely parallel to avast I´ve installed Firefox with Adblockplus 2.1.2 and Adblockplus-Popupaddon 0.4. Caused by the installation of this additional browser, before I´ve used Internet Explorer exclusively, there was no standard browser determined in Vista. After having declared the Internet Explorer again to be the standard browser, Avast doesn´t block internet URLs furthermore, neither when operated together with the Internet Explorer nor when operated together with Firefox.
Conclusion: There is some type of interference between Avast and the Vista Firewall.
It hasn’t got anything to do with avast, if you haven’t got a browser assigned as the default browser I don’t know how requests would be handled, i.e. the redirection of internet request.
If there were an issue between avast ‘free’ (which doesn’t have a firewall) and the Vista firewall then it really would be a hot topic in the forums. Yours is the first post to suggest this that I have seen.