“Network accounts are unavailable” when logging into OS X Lion Server
You can enter the username and password of the local administrator account at the login window you are seeing. The local administrator would be the user account that was created when first setting up OS X on the MacBook and is not associated with any network account server.

Once logged in to the local admin, open System Preferences, click on Users and Groups, unlock the preference pane, click on login options, and change "Display login window as" to "List of Users". You can also edit Network Account Server binding from the preference pane.