Try opening the control center and manually updating the program. This is one of AVG8's latest "quirks", as it seems it never manages to convince itself that all the latest patches have been applied. I think it has to do with the auto-update settings, it the update server isn't found at bootup, if gets pissed. That's the best I can explain it, as I stare at my own red "!". This is quite a stupid approach, since you need an internet connection open at startup, which is dangerous since any AV or firewall programs may or may not be fully operational when the system connects.
Bear in mind that I also have the "link scanner" disabled, which would cause the Red "!" as well. (even fully updated).
Have you ascertained that the program is functioning and that there is no infection causing the program to be disabled?