Windows 7 system automatically black screen back to the login interface case analysis

                  Problem Description
win 7 system will not automatically operate after a period of time, the system will automatically return to the login interface after the black screen, the screen saver has been set to "none" and the power management settings are "never", how to debug?

solutions
screensaver settings "to restore the login screen is displayed when the" check lead, deselect this option to solve the problem


problem analysis
this option in vista When the screen saver is "None" in the system and xp system, it is grayed out.
Windows vista system:

Windows XP system: