Windows XP Pro and domain account

At work I have a Windows XP Pro (SP2) workstation connected ad a windows
2000 server domain, if I disconnect the workstation from the net i can
log in onto it with the domain account.
At home I have set up a domain environment using a server with linux and
samba to mantain the password synced with my 2 windows xp workstation (2
Windows XP Pro SP2), but if I disconnect the laptop from the net I
cannot log in with the domain account, because it say:
"The system cannot log you on now because the domain <DOMAIN_NAME> is
not available."

I tried this KB article from microsoft:
http://support.microsoft.com/kb/172931/en-us
but it isn't useful (setting that value to 50 has no effect).

There is anyone who knows how I can use domain account if the network is
disconnected?
Thanks in advance

P.S.: sorry for my english

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Conver the Fagiolo