[Samba] Problem with XP

[Filippo Trocca]

I'm using samba 3.0.0 installed on a debian server.
I try insert a new account machine into samba, then a try to change 
computer name on my XP client machine. XP look at domain, ask my the 
username and password for enter into the domain. Then i have an error 
is impossible find the username on the domain.
I think I make some mistake when create the user. Ok I try to 
disconnect a machine just into the net and try to use the same machine 
name but I have the same error. I don't understand because.
Someone can help me?
Filippo

Sorry for my english