Michael,
Click Start, Run and type "control userpasswords2", and click Ok. ENABLE "Users must enter a user name and password to use this computer" option, and click Ok.

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Ramesh - Microsoft MVP
Windows XP Shell
http://www.mvps.org/sramesh2k
ExportZone - for Internet Explorer:
http://www.mvps.org/sramesh2k/ExportZone.htm
I was able to re-enable user switching by removing client
ware, however, when I turn on the computer it restarts in
the administrator account and not at the log on screen.
How can I fix this?