WinGuard Pro Free is a program that lets you lock some features of your
system so that nobody can use them while you are away. The program lets
you specify a password and then choose from a variety of options - what
features to lock, for example, the find tool, backing up, desktop, etc.
All the options are listed within one window and they are self-
explaining, so there is no need to wade your way through dozens of sub-
folders and weird registry key values.

The limited version of the program is free - you're asked as you first
install the program what version you would like to activate: the free one
or the shareware one. Download the program today and lock your Windows
from prying eyes."

http://www.winguardpro.com/