As a support engineer at Microsoft, I see almost daily some issues with Service Principle Names (SPNs). SPNs are as important to VMM communication as DNS. They are attributes on DNS entries that allow other services to find VMM. This is not a new issue, and this article covers how SPNs should be set up on your system. If everything is working well, please do not make changes. To see if you have SPNs registered correctly, at an elevated command prompt type ‘setspn –L <computername>’. This will list what is registered. You DO want to find SCVMM/Hostname and SCVMM/FQDN in the list. Below is only an example. Good luck with the article!
You may have problems with Virtual Machine Manager if some SPNs are missing http://support.microsoft.com/kb/2123063