Problem: When users are prompted for login credentials, the login screen defaults to an incorrect domain. While users can continue the login by providing their user name in domain\username format, non tech-savvy users find this annoying and confusing. This behavior may not be consistent from one client machine to another.
Cause: The client machine was joined to the wrong domain. This situation occurred after all users and computers were moved from one domain to another in Active Directory. The client machine in question was missed during the move of computers between domains, so that the machine retained a setting of the old domain. Windows Authentication defaulted to the domain of the client machine.
Resolution: Join the client machine to the correct domain. In Windows 7, with an account with admistrator privileges, Control Panel>System>Change Settings. On the Computer Name tab, click Change… Provide the full domain name. OK.
Many thanks to systems administrator Dino Jaha who discovered the root of this issue and provided the workaround.