Windows Steady State:

Lock down your user interface

Users sometimes go places and do things they shouldn't on shared machines. Now you can help protect sensitive locations and restrict user access to features such as Control Panel. Ever wish you could undo everything?

You can't always prevent problems during a user session, but now you can undo the whole session. Learn how Windows SteadyState can return your computer and hard disk to its exact condition before the user touched it, simply by rebooting.

I installed and used Returnil. It was a Giveawayoftheday freebie a little while ago. Returnil info at: http://www.returnilvirtualsystem.com/