I recently came across this while managing a clustered SQL Server. There were various messages listed out on forums, etc., but for me we found that the error was originating because we have DNS issues and Domain Controllers (DC) was unreachable due to a network switch configuration problem.
So if you see these errors, you may see in the EventLog a NetLogon error relating to not being able to reach a domain controller to login, and you will get the error below because the DC is the one that hands the Kerberos token to the process for use in SSPI related activities.
Logon,Unknown,Error: 17806 Severity: 20 State: 2.
Logon,Unknown,Login failed for user ”. The user is not associated with a trusted SQL Server connection. [CLIENT: IPAddress]
Logon,Unknown,Error: 18452 Severity: 14 State: 1.
Logon,Unknown,SSPI handshake failed with error code 0×80090311 while establishing a connection with integrated security; the connection has been closed.
Good luck and have a great SQL day.