It seems like their servers are stuffed because mine is getting disconnected as well...
Also as DavidR said, not much one can do about it, as this is an external connection issue and not a resident fault on your system.
It's the servers. Not surprised, as Avast! is and will always be a prime target for black hats.
Just updated to version 8 via clean install, and last streaming update noted was 3/30/2013 (using the month/date/year convention used by avast! here) @ 7:33:42 AM when I still had version 7 running, so... wait it out and it will be fixed. Connected, not connected, connected, not...etc., until fixed. This is only a symptom, not an error in your avast! installation.