[Samba] Samba4 - WinXP rpc server unavailable

[Zoltan Kiss]

Hi,

I have a test environment with Samba4 on Ubuntu 11.04 (alpha15 package), 
and a little problem around the joining to the domain from my WinXP SP3 
machine.
I followed the official Samba4 Howto, then my configuration steps was these:
  - Install smb4 from ubuntu package
  - setup provisioning, created a testdom.mycorp.local
  - setup bind9 with gssapi (everything working fine)
  - test authentication with kinit and klist
  - test cldap server with phpmyadmin (worked fine)

Then if i try to join from a Windows XP SP3 machine i got 'RPC server 
unavailable' error message. If i try with wrong user/pass then the 
correct error message appears - 'incorrect user etc.etc.'.
I have already disabled the Windows firewall, the Ubuntu box firewall 
and the Apparmor in Ubuntu, so i don't have any security app that 
prevents any communication (i think).

Samba log files are not showing any errors or warnings on 'log level = 
5', but it's not working.

Thanks for any help!

Regards,
Zoltan Kiss