Lock Desktops using group policy

To automatically lock users desktops using the password protected screen saver:

To lock desktops
Open the group policy editor and create or edit and existing Group Policy.

In the Group Policy editor go to:

User Configuration, Administrative Templates, Control Panel, Display
Enable – Password protect the screen sever
Enable – Screen saver timeout
Number of seconds to wait to enable the Screen Saver, (1500 Seconds = 25 minutes)