I got this today and called them since the forum was not accessible and I was concerned that Avast had been compromised in its own server or something using its own internet connection.
He did a remote look on my computer and insisted it is not Avast but some problem from faulty Windows or some remnant of some other, incompatible program like a registry key left from a long uninstalled Norton that came with the computer. He said it would be fixed if I paid a windows service tech every couple months to service the computer. So after 15 or a while minutes that is what he kept saying caused this, or using ccleaner, various things like that so that Avast could not function properly because of a faulty Windows or something from a 3rd party software and thus gave the message others have reported here.
I am not convinced this is the correct cause, but it is what was told to me by the Avast rep on the phone.