Do you have a P2P application, if so what is it ?

Do you mean you can’t enable it or it doesn’t work with your P2P program ?

All the Shields have a specific purpose and they look after certain functions. The Web Shield monitors http (port 80) web traffic, like your browser viewing http web pages. The Network Shield monitors common attack points used by internet worms, it is like a very limited Intrusion Detection System (not a full firewall). The P2P Shield monitors p2p application traffic.

So there are a number of Shields that if you don’t use those applications you don’t need, I would say your minimum would e Standard Shield, Web Shield, Internet Mail and the Network Shield.

I suggest a browse of the avast help file as all the Resident protection (shields) are covered.