2 Domains Showing Up during LOGON

Hi,
I have a Win 2000 network with 1 single domain. Let’s call it realdomain.com. Last month a coworker of mine was setting up a win2003 test server with a different domain. Let’s call it fakedomain.com. He ended up plugging the server to the real network and every client started to see these 2 domains as a choice when they try to logon to their machine..Or when they did Ctrl+Alt+del..So i disconnected that server off the network right away..BUT I still see that choice as part of the Logon. Does anyone know how to get rid of it so it does not show up when a client tries to logon?