This policy setting allows you to permit or prohibit use of the Control Panel Settings item and all preference extensions listed in the Group Policy Management Editor window of the GPMC under User Configuration\Preferences\Control Panel Settings. When the Control Panel Settings item or a preference extension is prohibited it does not appear in the Group Policy Management Editor window.If you enable this policy setting you permit use of the Control Panel Settings item and all preference extensions under Control Panel Settings for User Configuration. Enabling this policy setting overrides the "Restrict users to the explicitly permitted list of snap-ins" policy setting for the Control Panel Settings item but not for its children. Enabling this policy setting does not override any "Permit use of <extension name> preference extension" policy settings that are disabled.If you disable this policy setting you prohibit use of preference extensions under Control Panel Settings for User Configuration. Disabling this policy setting overrides any "Permit use of <extension name> preference extension" policy settings.If you do not configure this policy setting you permit use of preference extensions under Control Panel Settings for User Configuration unless restricted by the "Restrict users to the explicitly permitted list of snap-ins" policy setting or any "Permit use of <extension name> preference extension" policy settings.
Windows Components\Microsoft Management Console\Restricted/Permitted snap-ins\Group Policy\Preference snap-in extensions
User
At least Windows Server 2003 operating systems or Windows XP Professional with SP2
HKCU\Software\Policies\Microsoft\MMC\{127537A8-C1ED-40BC-9AE5-C5891DF6B2D4}!Restrict_Run
GroupPolicyPreferences.admx