This is because you do not have permission to open it, or you are on a windows server workstations and that snap in has been disabled. This would appear on programs like group policy editor or disk defrag.
You need to open them as an administrator.
Snap-Ins is the term used to refer to the specialized tools you can add to a console with mmc.
B. Local Users and Groups ~_~
B. Local Users and Groups ~_~
Active Directory Users and Computers is a snap-in. A snap-in cannot be started from a command line or from "Start" "run" it has to be started from an MMC (Microsoft Management Console). If you do not know how to create a Custom MMC let me know an I will walk you through those steps. you can use dsa.msc
to add functionality to standalone snap-ins
dsa.msc its a MMC snap in
Tools executed from a command line have an .exe file extension and MMC Snap ins have .msc file extension
Tools executed from a command line have an .exe file extension and MMC Snap ins have .msc file extension.
Encryption is not required
False
"Microsoft Management Console" - Control Panel - Administrative Tools
Group Policy Object Editor