samba - Sep 2008 - net rpc info failure accessing XP: NT_STATUS_LOGON_FAILURE

I'm trying to remotely shut down a Windows XP machine on my local 
network using "net rpc shutdown". I'm coming across errors, so I
decided
to back down to the simpler "net rpc info", thinking that there will
be
fewer security settings related to seeing things than actually shutting 
down the system. Here's the info for the two boxes in question:

----------------------------------
Linux box (Ubuntu 7.10):
brian@ireland:~$ uname -a
Linux ireland 2.6.22-15-386 #1 Wed Aug 20 18:11:25 UTC 2008 i686 GNU/Linux
brian@ireland:~$ net --version
Version 3.0.26a
brian@ireland:~$ net rpc info -I localhost -U samba%sambapass
Domain Name: BRIANS
Domain SID: S-1-5-21-3781685452-1013998031-819676632
Sequence number: 1221940999
Num users: 29
Num domain groups: 0
Num local groups: 0

Windows box:
Windows XP Professional, Service Pack 3
Full computer name: phoebus.
Workgroup: WORKGROUP
Shared folder: C:\share
Windows firewall: DISABLED
IP: 192.168.9.155

C:\share settings:
- Advanced/"not simple" file sharing
- Share name: share
- User limit: 10
- Permissions:
    - Everyone: Read
    - Lep (PHOEBUS\Lep): Full Control, Change, Read
---------------------------------

Here are the results of various commands when my XP box has 'Local 
Security Settings->Local Policies->Security Options->Network access: 
Sharing and security model for local accounts' set to 'Classic'
(please
note that "temppass" IS the current password for the Lep user):

brian@ireland:~$ net rpc info -I phoebus
Password: (** NONE GIVEN, JUST HIT ENTER **)
Could not connect to server 192.168.9.155
Connection failed: NT_STATUS_LOGON_TYPE_NOT_GRANTED

brian@ireland:~$ net rpc info -I phoebus
Password: notapassword
Could not connect to server 192.168.9.155
Connection failed: NT_STATUS_LOGON_TYPE_NOT_GRANTED

Connection failed: NT_STATUS_LOGON_FAILURE
brian@ireland:~$ net rpc info -I phoebus -U NotAUser%notapassword
Could not connect to server 192.168.9.155
Connection failed: NT_STATUS_LOGON_TYPE_NOT_GRANTED

brian@ireland:~$ net rpc info -I phoebus -U Lep
Password: temppass
Could not connect to server 192.168.9.155
The username or password was not correct.
Connection failed: NT_STATUS_LOGON_FAILURE

brian@ireland:~$ net rpc info -I phoebus -U Lep%temppass
Could not connect to server 192.168.9.155
The username or password was not correct.
Connection failed: NT_STATUS_LOGON_FAILURE

brian@ireland:~$ net rpc info -S phoebus -U Lep%temppass
Could not connect to server phoebus
The username or password was not correct.
Connection failed: NT_STATUS_LOGON_FAILURE

brian@ireland:~$ net rpc info -I phoebus -U //PHOEBUS/Lep%temppass
Could not connect to server 192.168.9.155
Connection failed: NT_STATUS_LOGON_TYPE_NOT_GRANTED

brian@ireland:~$ net rpc info -I phoebus -U PHOEBUS/Lep%temppass
Could not connect to server 192.168.9.155
The username or password was not correct.
Connection failed: NT_STATUS_LOGON_FAILURE

brian@ireland:~$ net rpc info -I phoebus -W WORKGROUP -U Lep%temppass
Could not connect to server 192.168.9.155
The username or password was not correct.
Connection failed: NT_STATUS_LOGON_FAILURE

-------------------------------------------

Here are the results when I have 'Local Security Settings->Local 
Policies->Security Options->Network access: Sharing and security model 
for local accounts' set to 'Guest only':

brian@ireland:~$ net rpc info -I phoebus
Password: (** NO PASSWORD, JUST HIT ENTER **)
Could not connect to server 192.168.9.155
Connection failed: NT_STATUS_LOGON_TYPE_NOT_GRANTED

brian@ireland:~$ net rpc info -I phoebus -U Lep%temppass
Could not connect to server 192.168.9.155
Connection failed: NT_STATUS_LOGON_TYPE_NOT_GRANTED

The NT_STATUS_LOGON_TYPE_NOT_GRANTED repeats for any command I try that 
actually connects to the server.

--------------------------------------------

Adding "share" to 'Security Options->Network access: Shares
than can be
accessed anonymously' has no noticeable affect. The security setting 
'Network access: Let Everyone permissions apply to anonymous users' is 
already enabled.

Does anyone have any ideas? I'm a bit stumped as to why a perfectly 
valid user can't log in.

Thanks much,
Brian