When I attempted to log on to my Samba domain from an XP workstation I got this:
Followed by this:
Except I'm not using roaming profiles.
The solution was to explicitly set the "logon path" and "logon home" parameters to nothing in the /etc/samba/smb.conf file:
logon path =
logon home =
I seem to remember a customer complaining about this in the past. Now I know.