Master Guard is a data security solution for Windows. It is a freeware file locking application that's light on system resources and well-designed.
Here is a screenshot to illustrate the features and user interface of this application:
Lock important files, folders or drives in order to protect them from unauthorized access, thanks to this program. Screenshot of Master Guard - 902px · 695px
Prey
Screen Blur
Deskman
WinLock
WinLock Professional