[Samba] smbclient -M --> ERRmsgoff?

[Wilkinson Charlie E]

Hi,
I've been a Samba user/admin for about a decade with relative success,
but now I'm stumped.  I'm hoping someone might be a solution to this, or
at least a solid answer.
 
I'm looking to send out winpopup messages to our XP clients when one of
our Samba fileshare servers needs to be rebooted.
 
So I'm trying to sending the messages from a Linux/Samba server, which
is not a member of a domain.  Clients are pre-SP2 XP Pro boxes, and are
domain (actually, active directory) members.  Using NET SEND from one XP
client to another, I can send winpopup messages all day long and drive
everyone nuts..  Using "smbclient -M <client IP> -I <server hostname>",
I get the ERRmsgoff error.
 
Since I know the messenger service is running and this appears not to be
a firewall problem, what am I left with?  Server not member of domain?
Is that the prime suspect?  Couldn't find any clues about that anywhere.
(Well... ok, I didn't check the source code yet....)
 
If it's some kind of authentication-based problem, I see that there's a
-U option to provide a username in -M mode, but no apparent option to
provide a password.  We have used such tricks in the past to print to an
XP domain client's shared printer.  Is there a similar way to
authenticate for sending winpopups?  Am I even barking up the right
tree?
 
If it helps, here's the response portion of the debug output:
 
...
Sent session request
got smb length of 0
size=0
smb_com=0x0
smb_rcls=0
smb_reh=0
smb_err=0
smb_flg=0
smb_flg2=0
smb_tid=0
smb_pid=0
smb_uid=0
smb_mid=0
smt_wct=0
smb_bcc=0
write_socket(3,62)
write_socket(3,62) wrote 62
got smb length of 35
size=35
smb_com=0xd5
smb_rcls=2
smb_reh=0
smb_err=82
smb_flg=136
smb_flg2=32769
smb_tid=65535
smb_pid=6188
smb_uid=0
smb_mid=2
smt_wct=0
smb_bcc=0
lang_tdb_init: /usr/lib/samba/en_US.UTF-8.msg: No such file or directory
message start: ERRSRV - ERRmsgoff (Not receiving messages.)

Is there enough info there to determine a specific cause?  Any clues
greatly appreciated!!
 
Thanks,
        Charlie
--
Charlie Wilkinson
SysAdmin, Programmer, etc...
Interactive Customer Contact Environment (ICCE)
Formerly: Telephone Routing & Interactive Systems (TRIS)
Phone: 202-283-3241   Phax: 202-283-5106
Charlie.E.Wilkinson at irs.gov <mailto:Charlie.E.Wilkinson at irs.gov> 

Modest people are #1!