smbclient fails on samba machine, but clients can connect

[Matthias Murra <Matt.Murra@gmx.de>]

I'm having a problem with smbclient hinted at above, maybe someone
on this list can help me out.

I am able to connect to the machine running the samba daemon from
other machines, browse shares, access, read and write files and so on.
smbd logs "connection from ..." and everything seems to work fine.

However, when I do
  smbclient -L <netbios name of server machine> -N
on the server (see test nr. 3 in diagnosis.txt), it fails and
smbd logs "refused connection from ...". How come? Samba appears
to work great besides this peculiarity, but I'd sure like to know
what is causing this message. I haven't found anything helpful
searching the debian mailing list archive and deja.com, though.

I will post smb.conf and the output of testparm if required.

TIA,
Matt