Suggestions anyone?
Install SP1 if you haven't. Reboot. Install SP2 if you haven't. Reboot.
Go to "Control Panel -> System and Maintenance -> System" and re-validate / re-activate your Vista.
There is a possibility that you would need to re-activate Vista before updating each SP (#1/#2), and then, after rebooting, that you would need to re-activate it again.
After each, any and all of the above steps, reboot.
Finally, download the latest stable version of avast, install it with "right click -> run as administrator" and reboot when the installation finishes.
