Swindmill,
What operating system and specs are you running?
If you are running XP, do you do your manual updates while logged on as an administrator or as a limited user?
I had similar problems with the User Interface and taskbar ball-->about avast! info screen updating the vps date info, when I tried updating while logged on as a limited user.
Try this,
Log on as administrator (no other user accounts running).
Go to Control Panel --> Add/Remove Programs --> Avast --> Repair (be sure you are connected to the internet beforehand).
Reboot.
Report your results back.
This said, assuming you have WinXP.

Acco