Avast Free 10.3.2225 on two Windows 7 64-bit systems, but it also happened with the previous release.
Livestream (http://www.livestream.com) chat will disconnect after a few moments. Happens in Firefox, IE, and Chrome. Avast gives no indication that it is blocking anything. If I disable the Avast Web Shield and reload the page, the chat will stay connected indefinitely in all 3 browsers, even if I re-enable the Avast Web Shield.