HELP - User is locked out

[Sherri MacCheyne]

Folks,

I have added a domain to an XP machine. However, whenever
I try to log this person in, I get the error:

You have been locked out of your Windows account. Contact
your System Administrator.

I am the System Administrator and don't know what to do
in this case.

Plesae tell me how I can unlock the user. I've tried all
the tricks I know.

thanks.