samba - Apr 2008 - failed to get machine password for account

Hi,

I have a samba server working as pdc, i have xp workstations joined to 
the samba domain working fine but suddenly since last week some of them 
can?t log into the domain and got an error message about the server is 
not available, the strange thing is the other machines can log in 
without problems.
In the /var/log/samba/smbd.log i got the following error when the 
machine tries to log in:

[2008/04/08 08:47:58, 0] rpc_server/srv_netlog_nt.c:_net_auth_2(461)
  _net_auth2: failed to get machine password for account pc_name$: 
NT_STATUS_NO_TRUST_SAM_ACCOUNT

I had to create a new machine account in the server and change the 
machine name in order to get into the domain. I will appreciate any tip 
in order to fix it up.
My OS is centOS 4.4 and samba 3.025xx

Regards,

--Ivan.