Well, there’s an option to set a password (Open user interface, select Settings, etcetera). If someone did play a prank on you by setting a password, I suppose the one reliable way out is to uninstall avast and install a fresh copy.
It might be worth trying to repair your present installation. Start | Control panel | Software | avast! whatever version you have | don’t uninstall, but repair.
I’m the only one that uses this computer, and I didn’t have a password for Avast 6.
In fact, all of this happened over a matter of minutes, Avast asked for a password for the first time when I restarted the system after the program update and tried to check out the settings.
I think this may be a bug.
I’m thinking of uninstalling-reinstalling now unless there is another solution.