from my memory there use to be a option under "administrative controls" in control panel that brought up a window with all user accounts, and u can "set PW to never expire" "disable account" etc etc.... where did it go?!?!?
Are you sure you aren't thinking of a domain/AD equipped pc? I've never seen what you're describing on a standard home pc but then again I've never really looked. I'd be interested to know the answer to your question as well.