DC had problems with replicating so needed to dcpromo down and back up to fix. All went good. The same name was used. All ok. Sysvol and Netlogon also created etc. DHCP still avail. DNS ok. Now the clients that authenticate with the DC cannot log onto domain after they have been rebooted. Says: "Windows cannot connect to the domain because controller is down or otherwise unavailable or because your computer account was not found. "