Auto Lock is a very useful tiny little free program/app that will enable users to perform actions such as lock, log off, restart or shutdown for their desktop / laptop / tablet PCs when the device has not been used for a certain period of time. It is a freeware automation locking application that's light on system resources, portable, well-designed and attractive.
Here is a screenshot to illustrate the features and user interface of this application:
Prey
Screen Blur
Deskman
WinLock
WinLock Professional