Screen Saver Unable to Switch to Lock Function Automatically

In order to protect your computer contents while leaving the computer on and you need to be away for a while without shutting down the computer, windows provides a very simple features by locking out your computer through screen saver mode. By pressing the Windows Key and L key at the same time on the keyboard, you can lock your computer manually without leaving your computer contents ‘bare naked’ for everybody to see. To resume back to windows system to continue what you are doing, you will need to enter your password to relogin.

The windows system screen saver mode will also locked off automatically after a period of time when the window system remains inactive. The timing can be set at Screen Saver Settings option as according to user preference.

Start > Control Panel > Personalization > Screen Saver.

However, some users may also experience abnormal issue that the windows will not lock automatically after the inactive period. If you have confirmed the screen saver settings is not the cause, you may consider to check on network adapter power management.
Start> Control Panel> Device Manager> Network adapters
Select on the network adapter (Right Click) > Properties > Power Management
Uncheck the box “Allow this device to wake the computer”.