In the SharePoint install document I have it says, If you use a domain user account for the SQL Server service account, you must make sure that a valid service principal name (SPN) for that account and instance of SQL Server on their database server exists in their environment. This is the case regardless of whether you use NTLM or Kerberos authentication for Office SharePoint Server 2007. You must configure the SPN for that account in the domain using the Setspn.exe command-line tool. Setspn.exe is installed by default on computers running Windows Server 2008. Run the following command on a computer that is joined to the same domain as the user/service account. setspn -a <http/<farmclusterdnsname> <serviceaccountname> What should the parameters be in this case? I guess the serviceaccountname would be 'domain\username' not sure what the first parameter should be though. This is the technet link for SetSPN.