If the screen saver and screen lock are both enabled (On) and the Start Lock value is smaller than the Start Saver value, when the screen lock times-out it replaces the contents of the screen with the currently selected screen savers. If Start Lock is greater than Start Screen, then the automatic screen lock simply continues the current screen saver.
If the screen saver is disabled (Off) and automatic screen lock is enabled (On), when the screen lock times-out the contents of the screen are not covered with a screen saver.
Select the settings you want:
Screen Lock: Enables (On) or disables (Off) Screen Lock on a timeout. When this setting is changed, the new setting goes into effect immediately, even before the dialog box is closed.