Hi,
we have the same problem with 2.0.7pre4 running under Digital Unix 4.0e 
(Tru64 UNIX). In the logs we get the following errors (replaced IP 
addres with fake ones):
Apr 25 17:24:29 master nmbd[29559]: [2000/04/25 17:24:29, 1] 
nmbd/nmbd_processlogon.c:process_logon_packet(70)
Apr 25 17:24:29 master nmbd[29559]:   process_logon_packet: Logon from 
X.Y.Z.W: code = 12
Apr 25 17:24:29 master nmbd[29559]: [2000/04/25 17:24:29, 0] 
lib/fault.c:fault_report(40)
Apr 25 17:24:29 master nmbd[29559]:   
==============================================================Apr 25 17:24:29
master nmbd[29559]: [2000/04/25 17:24:29, 0]
lib/fault.c:fault_report(41)
Apr 25 17:24:29 master nmbd[29559]:   INTERNAL ERROR: Signal 11 in pid 
29559 (2.0.7-pre4)
Apr 25 17:24:29 master nmbd[29559]:   Please read the file BUGS.txt in 
the distribution
Apr 25 17:24:29 master nmbd[29559]: [2000/04/25 17:24:29, 0] 
lib/fault.c:fault_report(43)
Apr 25 17:24:29 master nmbd[29559]:   
==============================================================Apr 25 17:24:29
master nmbd[29559]: [2000/04/25 17:24:29, 0]
lib/util.c:smb_panic(2381)
Apr 25 17:24:29 master nmbd[29559]:   PANIC: internal error
Apr 25 17:24:29 master nmbd[29559]: 
were X.Y.Z.W machine is a Windows 2000 Professional. I only did a "net 
use" from the professional machine to access a share in the MASTER 
machine.
Any idea about what's happening?
PS: I got the same problem in a 'slave' machine in the same samba 
domain (the problem was that the a Windows machine had an incorrect IP 
address for the WINS server). But, why this cause a PANIC? The logs are:
[...]
Apr 25 16:48:02 slave nmbd[18658]: [2000/04/25 16:48:02, 0] 
nmbd/nmbd_incomingrequests.c:process_name_refresh_request(180)
Apr 25 16:48:02 slave nmbd[18658]:   process_name_refresh_request: 
unicast name registration request received for name LLANTA<03> from IP 
147.83.54.21 on subnet UNICAST_SUBNET.
Apr 25 16:48:02 slave nmbd[18658]: [2000/04/25 16:48:02, 0] 
nmbd/nmbd_incomingrequests.c:process_name_refresh_request(181)
Apr 25 16:48:02 slave nmbd[18658]:   Error - should be sent to WINS 
server
Apr 25 16:48:09 slave nmbd[18658]: [2000/04/25 16:48:09, 0] 
lib/fault.c:fault_report(40)
Apr 25 16:48:09 slave nmbd[18658]:   
==============================================================Apr 25 16:48:09
slave nmbd[18658]: [2000/04/25 16:48:09, 0]
lib/fault.c:fault_report(41)
Apr 25 16:48:09 slave nmbd[18658]:   INTERNAL ERROR: Signal 11 in pid 
18658 (2.0.7-pre4)
Apr 25 16:48:09 slave nmbd[18658]:   Please read the file BUGS.txt in 
the distribution
Apr 25 16:48:09 slave nmbd[18658]: [2000/04/25 16:48:09, 0] 
lib/fault.c:fault_report(43)
Apr 25 16:48:09 slave nmbd[18658]:   
==============================================================Apr 25 16:48:09
slave nmbd[18658]: [2000/04/25 16:48:09, 0]
lib/util.c:smb_panic(2381)
Apr 25 16:48:09 slave nmbd[18658]:   PANIC: internal error
Apr 25 16:48:09 slave nmbd[18658]: 
Parts of the 'smb.conf' in these machines:
*** MASTER ***
  server string         = Master SERVER
  netbios name          = MASTER
  security              = USER
  workgroup             = OURWG
  domain master         = Yes
  local master          = Yes
  preferred master      = Yes
  os level              = 65
 
  wins support          = Yes
  lm announce           = No
  lm interval           = 0
 
  name resolve order    = wins host
  dns proxy             = No
 
  domain logons         = Yes
  domain logons         = Yes
  logon script          = logon.bat
  allow trusted domains = Yes
  encrypt passwords     = Yes
  smb passwd file       = /usr/local/samba/private/smbpasswd
*** SLAVE ***
  server string         = Slave SERVER
  netbios name          = SLAVE
  security              = DOMAIN
  workgroup             = OURWG
 
  domain master         = No
  local master          = No
  preferred master      = No
  os level              = 0
 
  wins support          = No
  wins server           = A.B.C.D (IP address of MASTER machine)
  lm announce           = No
  lm interval           = 0
 
  name resolve order    = wins host
  dns proxy             = No
  domain logons         = Yes
  logon script          = logon.bat
  password server       = MASTER
  allow trusted domains = Yes
  encrypt passwords     = Yes
  unix realname         = Yes
_____________________________________________________________________
  o o o   MANEL Rodero                   | Laboratori de Calcul FIB
  o o o   TGS TIC (Analyst)              | Campus Nord - Modul B6
  o o o   Laboratori de Calcul FIB       | Jordi Girona, 1-3
  U P C   FIB - UPC                      | 08034 Barcelona (Spain)
                                         |
  Email : manel@fib.upc.es               | Tel : +34 93 401 6943
  WWW   : http://alabi.fib.upc.es/~manel | Fax : +34 93 401 7040
_____________________________________________________________________