Windows cannot delete %2 because it contains the critical system object %3. If you want to delete this container, you must ...

Windows cannot delete %2 because it contains the critical system object %3.
If you want to delete this container, you must first use Find to locate %3 and delete it or move it to another container.  If objects are still not available for deletion go to the view menu and check "Users, Contacts, Groups, and Computers as containers" and "Advanced Features".