samba - Dec 2006 - 3.0.23c (FC6) and XP Pro - Error: STATUS_OBJECT_NAME_NOT_FOUND

On Monday (xmas day) samba was working fine.  On Tuesday it wasn't.  I
didn't change anything on either the Fedora Core 6 machine (relay) nor
the XP Pro machine (oob2).

I followed all the steps in "Procedure 38.1. Diagnosing Your Samba
Server", and until I got to step 8 everything worked fine.  From the
broken xp pro machine:

   oob2$ net view '\\relay'
   The Server service is not started.

   More help is available by typing NET HELPMSG 2114.

   oob2$ 

(`relay' is the `fc6' machine.  `oob2' is the broken xp pro box.)

The `server' service is running.  I stopped and started again
countless times, and rebooted the xppro machine.

I uninstalled samba from the fc6 machine (saving /etc/samba/smb.conf
and restoring it afterwards... see below).  Same problem after
reinstallation.

I can "view" other machines (an xppro machine) on the broken
xppro machine:

   oob2$ net view '\\dude'
   Shared resources at \\dude

   kevin's computer

   Share name  Type  Used as  Comment  

   ----------------------------------------------------------------------------
   c           Disk                    
   The command completed successfully.

   oob2$ 

I downloaded wireshark 0.99.4 and found the point at which the good
xppro (dude) and bad xppro (oob2) machines diverge:

   good:
   dude -> relay: NT Trans Request, NT CREATE
   relay -> dude: Nt Trans Response, NT CREATE, FID: 0x4000

   bad:
   oob2 -> relay: NT Trans Request, NT CREATE
   relay -> oob2: Nt Trans Response, NT CREATE,
		  Error: STATUS_OBJECT_NAME_NOT_FOUND

So, I turned on debugging in smbd, and see this, which lines up
perfectly with the wireshark output:

[2006/12/27 14:01:05, 5] auth/auth_util.c:debug_unix_user_token(474)
  UNIX token of user 500
  Primary group is 100 and contains 1 supplementary groups
  Group[  0]: 100
[2006/12/27 14:01:05, 5] smbd/uid.c:change_to_user(260)
  change_to_user uid=(500,500) gid=(0,100)
[2006/12/27 14:01:05, 4] smbd/vfs.c:vfs_ChDir(741)
  vfs_ChDir to /tmp
[2006/12/27 14:01:05, 5] smbd/nttrans.c:call_nt_transact_create(1117)
  call_nt_transact_create
[2006/12/27 14:01:05, 4] smbd/nttrans.c:nt_open_pipe(325)
  nt_open_pipe: Opening pipe srvsvc.
[2006/12/27 14:01:05, 3] smbd/error.c:error_packet(146)
  error packet at smbd/nttrans.c(340) cmd=160 (SMBnttrans)
NT_STATUS_OBJECT_NAME_NOT_FOUND


Thinking it might have to do with cruft in /tmp, I removed everything
that `lsof' said wasn't open by something (all but 2 files, unrelated
to samba). 

Here's my /etc/samba/smb.conf file:

[global]
   workgroup = FRANZ
   server string = Samba Server
   security = user
   log file = /var/log/samba/%m.log
   interfaces = 192.168.0.0/24
   allow hosts = 192.168.0.0/24
   bind interfaces only = yes
##### disable printing completely:
   load printers = no
   printing = bsd
   printcap name = /dev/null
   disable spoolss = yes

[homes]
   comment = Home Directories
   browseable = no
   read only = no
   create mode = 0750

[tmp]
   comment = /tmp
   path = /tmp
   valid users = layer
   public = no
   writable = yes
   create mask = 0755

...

Ideas?  I'm fresh out.  I have no idea how to debug this further.

Thanks.

Kevin