See Vlk’s solution for this: http://www.avast.com/forum/index.php?board=2;action=display;threadid=1610;start=msg9952#msg9952
Other related threads: http://forum.avast.com/index.php?board=2;action=display;threadid=2981 http://forum.avast.com/index.php?board=2;action=display;threadid=4039 http://forum.avast.com/index.php?board=2;action=display;threadid=3902 http://forum.avast.com/index.php?board=10;action=display;threadid=4590 http://forum.avast.com/index.php?board=10;action=display;threadid=5819
Hope this help :-[