I've had the same problem! That's a pity!!!
Recently Avast HE is causing to me lots of problems (take a look
HERE). I'm so sorry about this, because I use this antivirus since times ago.
My (pure and original) O.S.: Windows XP Professional (updated).
I upgraded Avast! Free Antivirus to version 6.0.1203. Since that I need to re-activate my O.S..
Something more.
If I re-activate the O.S., leave "opened" my internet connection (I don't disable the LAN connection) and shut down the pc (sorry for my english!!!), at the restart, I have no problems.
Otherwise, if I close my connection, then shut down the pc, restarting it (or shutting down then starting again), I receive a message to active (in 3 days) my O.S..
So ... I uninstalled Avast! ...
Spyware Terminator comes to function regularly (because it can load the upper frame on the right ... as I supposed), but I still have the activation problem.
Now I'm restoring an old image (made with Acronis) of my pc ... I'll tell you.
I'm so sad about this ...