When you try to add your Windows 2000 computer to a Windows NT 4.0 domain, you receive:
Your computer could not be joined to the domain because the following error has occurred: The security database on the server does not have a computer account for this workstation trust relationship.
This error can happen if you don't have administrative privileges or if your username contains a spaces.
To workaround this issue:
1. If your username contains a space, configure a new username.
2. Open a CMD prompt and type:
NET LOCALGROUP Administrators "Domain Name\UserName" /add