A TechNet Wiki topic regarding Kerberos error 0x7 has just been posted http://social.technet.microsoft.com/wiki/contents/articles/kerberos-error-code-0x7-kdc-err-s-principal-unknown.aspx based on the popularity of the forum thread http://social.technet.microsoft.com/Forums/en-US/winserverDS/thread/5e282685-522c-4ce0-9ee2-e9d9a5d1f76f. This article consolidates the information in that forum thread and helps to point the way to articles that will provide troubleshooting steps for the situation.