Found a possible bug with the self-defense module.
I'm running this pre-release (4.8.1178) on Win XP SP2 Pro, and I went into Services and try to stop the avast! service, and do get a warning. With this pre-release I noticed that the "No" buttons has an auto countdown, and decided to leave it and see what happens ... It was not what I expected, it counted down, disappeared and allowed the avast! service to stop.
I can confirm the service stops since it shows that little red circled-stripe on the avast! logo in the system tray and I'm able to extract the EICAR test virus with no detection what so ever.
Might be something you would want to look into.
-- Sauron