Thats ok, everyone is new at sometime, I was newbie a short few months ago. Just avoid, as a rule, making "blanket statements" like "Avast! doesnt work with Win7" or as you said, "Avast! P2P shield dont work", etc.
These posts show up not just here, but on big name search engines. If another person has a similar problem as you, they search, and one of the first results they see is your post. So if any program, from firewall to browser all the way down to the O.S., causes a problem with the P2P shield, they will read your post and latch onto the idea that your single statement presents, that a component of Avast! is broken.
Then soon, you have 2-3 people who think a pandemic has struck their A.V., that there are 100's or 1000's with the same problem, which is of course false.
So the correction was only a little for you, more to set the public record straight.
But as for your problem, does the traffic history or report file from the Avast! UI show any activity at all, as in, Is the module even running? (Open Avast!>>Realtime shields>>P2P shield>>2 buttons at bottom of window )