When I try and edit the default domain controller policy from Directory Management MMC the local policy is shown, why?

Start the Directory Management MMC (Start - Programs - Administrative Tools- Directory Management)

Select the domain and right click on "Domain Controllers" andselect Properties

Select the 'Group Policy' tab

The policies in effect will be shown, normally 'Default Domain ControllersPolicy". If you select it and click Edit the Group Policy editor MMCshould start with "Default Domain Controllers Policy" as its root.You can then make changes

Start the registry editor (regedit.exe)

Move to HKEY_CLASSES_ROOTMSCFileShellOpenCommand

Double click on (Default)

If the line reads
D:WINNTSystem32MMC.EXE "%1"
(your NT installation location may be different) Add %* to the end, e.g.
D:WINNTSystem32MMC.EXE "%1" %*

Click OK