this is the same old problem that Avast never resolve:
http://forum.avast.com/index.php?topic=116901.30
http://forum.avast.com/index.php?topic=115742.0
http://forum.avast.com/index.php?topic=125784.0
this happens also with normal internet connection,not only with VPN.remove AIS means losing the connection.
I do not know what to expect to solve this huge problem!