On a computer that is running Windows Server 2008, you create a local user account that is a member of the Local Administrator group. Then, you add the Terminal Server server role. After you do this, the user's icon and name are not displayed on the local server's logon screen.
In Windows Server 2008, this behavior occurs when you add the Terminal Server server role to a server. When you add this role, the Interactive logon: Do not display last user name
Group Policy setting is enabled. By default, this setting is disabled.
This behavior is by design.