This policy setting allows you to permit or prohibit use of the Scheduled Tasks preference extension. When a preference extension is prohibited it does not appear in the Group Policy Management Editor window of the GPMC.If you enable this policy setting you permit use of the preference extension unless restricted by the "Permit use of Control Panel Settings (Computers)" or "Permit use of Control Panel Settings (Users)" policy settings. Enabling this policy setting overrides the "Restrict users to the explicitly permitted list of snap-ins" policy setting.If you disable this policy setting you prohibit use of the preference extension.If you do not configure this policy setting you permit use of the preference extension unless restricted by the "Restrict users to the explicitly permitted list of snap-ins" "Permit use of Control Panel Settings (Computers)" or "Permit use of Control Panel Settings (Users)" 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\{CAB54552-DEEA-4691-817E-ED4A4D1AFC72}!Restrict_Run
GroupPolicyPreferences.admx