[Samba] 3.5.4-0.70.el5_6.1 logon problems with Windows 7

[Samba]

Hello, 

I am running Samba 3.5.4-0.70.el5_6.1 on a Centos 5 machine. 

I have recently installed a Windows 7 Ultimate x64 workstation. Joining 
the Samba domain was successful however I am unable to login onto the 
machine with this domain. On my Windows XP64 bit it works ok. 

The error message windows is giving me is: 

"There are currently no logon servers available to service the logon 
request" 

However, when I login with a local account, I can access all the shares I 
have made on the Samba server without any problems..... 

The following data is found in the SMBD log when trying to logon with the 
Windows 7 machine: 

[2011/08/06 16:56:13.709464,  0] lib/util_sock.c:474(read_fd_with_timeout)
[2011/08/06 16:56:13.709782,  0] 
lib/util_sock.c:1441(get_peer_addr_internal)
 getpeername failed. Error was Transport endpoint is not connected
 read_fd_with_timeout: client 0.0.0.0 read error = Connection reset by 
peer.
[2011/08/06 16:56:13.722554,  1] smbd/server.c:267(remove_child_pid)
 Scheduled cleanup of brl and lock database after unclean shutdown 

What is going wrong here? How can I fix this, so that the Windows 7 
machine can correctly logon? 

Thanks for all the help! 

Kind regards, 

Raymond