Today Avast released a bad antivirus definition file “110411-1″ in which its web filter detected false positives for what seems to be most websites.

I found the official information from Avast about it on their Twitter feed.  Their forums were down.  (overloaded?)  Their update servers were taken down to prevent more people from getting the bad updates until the new fixed update 110411-2 has been released.

Now the update servers are online again, so if you are experiencing false positives for Avast, go ahead and have Avast update itself and it will be fine again.  (Or wait for it to update itself on its own)