See this foruns:
http://www.avast.com/forum/index.php?board=2;action=display;threadid=1320;start=msg7337#msg7337
http://www.avast.com/forum/index.php?board=2;action=display;threadid=268;start=msg5869#msg5869
http://www.avast.com/forum/index.php?board=2;action=display;threadid=967;start=msg5172#msg5172