Ok. after lurking around other threads I think I found the possible solution. Disabling self defense module might be the answear.
http://forum.avast.com/index.php?topic=119008.30 http://forum.avast.com/index.php?topic=121404.0 http://forum.avast.com/index.php?topic=121440.0 http://forum.avast.com/index.php?topic=121436.0
I guess I should search first next time before asking.