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

When bringing a new server on line, you may see an error that says:

The Security System detected an authenticaton error for the server ldap/xxxxxxxt.
The failure code from the authentication protocal Kerberos was "There are currently no logon servers available to service the logon request.
Event id: 40960
category: SPENGO (Negotiator)
(0xc000005e)

This issue is the result of missing or the inability to contact the DNS SRV (SeRVice) records.

You just brought a new server on line. To complete the process, the server has to register its own host A record and SVR record in DNS. To do this, Type the following at the command prompt:
IPconfig /flushdns
IPconfig /registerdns
net stop netlogon
net start netlogon

flushing DNS will remove all old or improper DNS records
registering dns records registers your Host A record
restarting the netlogon will register your SRV records.
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Speaking of SRV records, here is your second potential problem: (For 2003 server ONLY)

2003 server has a quirk in it. When the netlogon service is restarted it registers the SRV record of both NICs on the DNS server. As you know DNS is the service that provides the DNS translation to the Authenticating server. If DNS sees two SRV records, Cityofabbeville,int picks up on the NIC that shouldn't be providing DNS to the clients, you may get "no netlogon servers can be found" for your authentication server and see the errors above.

The quirk in 2003 server is regardless of deselecting the option registering the SRV record when netlogon is restarted, it will still register the SRV record. There is a patch to resolve this. But, let's make sure this is the problem. Go into DNS and see if your multihomed DNS server has two SRV records. One will be internal and the other external of your LAN. If you have an SRV record that doesn't belong, you should remove these records. This is only a temp fix for troubleshooting because upon a restart of the netlogon service will put those records back in DNS.  

Then, I would go to the XP clients and check out the IPconfig /all. See if you have picked up on a DNS server that is not correct. If so, you will not be able to get the DNS query for the Authenticating server to propogate back. So, you will not be able to communicate with the Authenticating server. Hence, you will not be able to authenticate and recieve errors like you are seeing. Flush the DNS cache and manually configure your list of preferred DNS servers to the correct NICS.

There is a fix to the 2003 server. It is a patch.
Have a look at this:
 -- http://support.microsoft.com/?id=832478
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Now, It is time to try and force replicate:
To force replicate, and save yourself time:
a) go to the Active Directory Sites and Services Snapin
b) navigate to Default First Site>>Servers
c)Pick the server you want to replicate TO and expand it
d)right click what is showing (NTDS site?) and select "replicate now"


Your DC's will replicate in approximately 8 hours after making it a domain server. The force replication is used to save you the eight hours.       

If your 4960 SPNego error persists, please post a question in Experts Exchange server zone that defines what server you are currently using?