The AVG Forum is inundated - they've obviously shot themselves in the foot over the last couple of days.
Not answering any more queries on it - just saying that you will stay protected except for very latest Virus defns - and a fix is imminent..... hopefully.
Dont be tempted to deinstall, download and reinstall
Mine came up with this this morning and here's how I fixed it... double click the avg icon in my system tray (bottom right - sorry I have no idea how computer literate you are, so forgive me if I explain the obvious) That brings up an AVG panel. One option on there (last one on mine) is update manager and is/was red instead of green (because it's not up-to-date) Double click "update manager" Then click the "update now" button.
It sorted itself out no problem and my PC is all happy again =)
Oh incase it makes any difference, I'm running on Vista, have office 2007, never defrag (and never have problems because of it)