We ran into an SSPI issue when trying to use the CRM PluginRegistration tool against an Org recently created / populated with Solutions.
In our case, the root case was clock synchronization. Our Domain Controller had the correct value for date / time (or at least within several seconds of the time.gov time). Our CRM machine, however, had the wrong value for date. In our case it had the value for tomorrow. Our Domain Controller and CRM VMs were hosted on separate hosts, and the CRM VM's host was setup with the wrong date.
Once we corrected the on the VM host and ran w32tm /resync on the CRM VM ... the problem disappeared.
This is the umpteenth time I've seen varieties of clock-drift causing SSPI errors. Recall there is a 5-minute tolerance between the client and server on web service traffic over Kerberos.
Hope this helps someone.
Howard Hoffman