If you disable this setting, screen savers do not run. Also, this setting disables the Screen Saver section of the Screen Saver tab in Display in Control Panel. As a result, users cannot change the screen saver options.
START > RUN > GPEDIT.MSC > USER CONFIGURATION > ADMINISTRATIVE TEMPLATES > CONTROL PANEL > DISPLAY > FIND SCREENSAVER > RIGHT CLICK PROPERTIES > CLICK DISABLE > OK
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By default, the policy key value does not exist.
OR just set the screen saver to None on the Display Properties control panel page (See Microsoft article KB811460). For more info see: http://technet.microsoft.com/en-us/library/cc959132.aspx.
Note: This setting does NOT stop the Windows Logon screen saver from running under the Default user (ie when no one is logged on); see Microsoft article KB314493 for more info).