Troubles connecting different versions of Samba

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I just upgraded my distro, and now I have Samba 3. I use it as
client only, and it can connect normally to every Windows PC in
the LAN, mounting shares and so on, but it gives error

Anonymous login successful
3941: tree connect failed: ERRSRV - ERRbadpw (Bad password -
name/password pair in a Tree Connect or Session Setup are
invalid.)
SMB connection failed

when I try to mount the share on my Samba server (shares listing
with smbclient -L works though), that has version 2.2.8a.
Before upgrading, the client connected normally to this server,
and the smb.conf was the same.

Client:
Slackware linux 10.0
Samba 3.0.4
<smb.conf>
[global]
********workgroup*=*DOMUS
</smb.conf>

Server:
Slackware linux 9.0
Samba 2.2.8a
<smb.conf>
[global]
********workgroup*=*DOMUS
********netbios*name*=*FAMULUS
********interfaces*=*lo*eth0
********bind*interfaces*only*=*Yes
********encrypt*passwords*=*Yes
********printcap*name*=*cups
********preferred*master*=*Yes
********domain*master*=*Yes
********hosts*allow*=*192.168.57.
********printing*=*cups
********follow*symlinks*=*No

[samba]
********comment*=*cartella*condivisa
********path*=*/home/samba
********force*user*=*smbuser
********force*group*=*samba
********read*only*=*No
********create*mask*=*0600
********force*create*mode*=*0600
********security*mask*=*00
********force*security*mode*=*0777
********directory*mask*=*0700
********force*directory*mode*=*0700
********directory*security*mask*=*00
********force*directory*security*mode*=*0700

[printers]
********comment*=*All*Printers
********path*=*/var/spool/samba
********printer*admin*=*root
********printable*=*Yes
********browseable*=*No
</smb.conf>

- --
Dario Basile
- ----------------------------------------------------------------
Hic (in mona) manebimus optime.

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