Disable Screen Saver

To disable a screen saver that has been enforced by Group Policy, open the registry and delete the following keys under HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\Control Panel\Desktop
ScreenSaveActive REG_SZ 1
ScreenSaverIsSecure REG_DWORD 00000001
ScreenSaveTimeOut REG_SZ 1800