According to Microsoft – http://support.microsoft.com/kb/321044/en-us
This problem occurs because two or more computer accounts have the same service principal name (SPN) registered. Event ID 11 is logged when the Key Distribution Center (KDC) receives a ticket request, and the related SPN exists more than one time when it is checked on the global catalog (GC) for forestwide verification. My simple explanation is that the original process of switching SERVER1 to a new temporary name didn’t go right.
The fix was pretty painless. On the problem server open up a command line and type the following replacing SERVERNAME with the problem system (In this example SERVER1)
note-the first character is an l and not the number 1
ldifde -f c:check_SPN.txt -t 3268 -d “” -l servicePrincipalName –r “(servicePrincipalName=HOST/ServerName*)” -p subtree
Now find the file check_SPN.txt on your drive
The contents of the check_SPN.txt file that is generated should show something similar to the following. Using the following output information SERVER1 is the system we are having trouble with. SERVER2 is no longer in service. As you can see the second portion of the output has a mix of both SERVER1 and SERVER 2 in its output
Hop into your domain controller and open “Active Directory Users and Computers” and right-click on your domain. Click “Find” and change the drop down option to “Computers”. Type the server name that is the equivilent to SERVER2 in the above example and DELETE it. You should now be able to login to SERVER1 and carry on with your day!