"Windows cannot connect to the domain, either the Domain Controller is down or because the computer account was not found" I deleted DNS entries and re-added to domain. These were are few remaining 2000 machines and a couple servers. Everything works after the re-add. I upgraded backup exec to 11d on a domain controller. After that is when the issues started. Any ideas. Just want to understand what happened here. Could it be anything to do with sql upgraded?