Using the W2K style login this can happen from the Workgroup/Domain name
being wrong under System Properties/Computer Name/Change. You will need to
boot into the Admin account and make the proper changes.
A similar error appears for Welcome Screen users when an Admin Account
password has been set for Auto-Logon and not the intended profile. If this
is the case: On Pro Edition, from the Welcome screen, press ctrl-Alt-Delete
Twice. On Home, boot to Safe Mode, and logon.
Make the change under Control Panel/User Accounts.