[Samba] problem adding windows machines to domain - user root not found

[Matt Singerman]

Hello all,

I am trying to add a Windows XP machine to a domain controlled by a Samba 3 
server.  The problem is, when I try to add it, I get the follownig error:

"Your computer could not be joined to the domain because the follownig error 
occured:

The user name could not be found."

I am using the username root and the root samba password.  I even changed 
root's samba password to make sure I was using the correct one:

speedy# smbpasswd root
New SMB password:
Retype new SMB password:
speedy#

Still no luck.  Other computers are on the domain and running fine, and in 
fact I have previously added new machines to it!  I am completely flummoxed 
here.  Any ideas?

Thanks,

Matt