Besides pk advice…
Take a look at
http://www.avast.com/forum/index.php?board=2;action=display;threadid=1395
http://www.avast.com/forum/index.php?board=2;action=display;threadid=1398
http://www.avast.com/forum/index.php?board=2;action=display;threadid=1244
http://www.avast.com/forum/index.php?board=2;action=display;threadid=1399

Maybe some post could help you…