I don't know if this is the same issue as with Dells, loading their drivers early, etc. but some of those have uninstalled the Behaviour Shield (BeS) as a temporary measure until this is resolved in a program update.
So if one of you with an Acer with this problem (my little win7 acer d255 netbook doesn't) could try uninstalling the BeS and report if that works.
From windows add remove programs, Avast! xxx, click the Change/Remove button; from the new window select the Change section; from the list of Shields, uncheck the one for the Behaviour Shield and OK your way out. Now reboot and see if that resolves the problem.
This may be better than disabling the acer software as it is also relatively east to reverse this after any avast program update.