I'm adding a Login to SQL Server 2000. I press the "..." button next to the name field, select a user or group name from the list of domain groups and users, attempt to finish adding the Login and receive "Error 15401: Windows NT User or Group 'domain\user' not found. Check the name again." This happens with almost all domain users (two work; one is also a local user while the other is not), just some; but it does happen with all domain groups (copying one of the ones that works to another name does not work). I've been through MS KB #324321 with no luck. I would think that if it could find the name to add it to the list, then it could find the name to authenticate it as a valid name (but I'm not a MS programmer ...).

Configuration Details: SQL Server 2000 SP3 on Windows Server 2003; member of domain whose domain controller is Windows 2003 Server Enterprise Edition.