ScreenLock

ScreenLock is a file-security program that is designed to provide easy yet secure access to your computer while denying others' attempts to use that computer.

You can configure ScreenLock to prevent Windows from starting without the proper password, or start ScreenLock quickly if you must leave your PC running and unattended. Attempts at access are logged, and the time of the attempt is viewable in the access log. Hot keys can instantly lock your computer from any other application. ScreenLock can be set as your screensaver. This version uses less resources and has improved hot key operation.