This isuue is also reported in Japanese forums (about Ragnarok Online).
http://forum.avast.com/index.php?topic=72344.0

Currently this issue happens only with Vista 32bit environment, and only solution is downgrade to 5.x.

… yeah I don’t like Gameguard either, but I hope avast! team fix this issue. Now I can see some users start to tell others quitting avast only because this happens :cry: