Cannot generate SSPI context.
Today I was getting the above error while trying to connect to SQL Server instance.
After some research found that this is related to the registration of the Service Principal Name (SPN) for SQLServer.
The solution to this problem was
1) Change the SQL Server Service to run under 'LOCALSYSTEM' account and restart SQL Server.
2) Once this was complete I was able to connect to the instance.
3) Next change the service to run under whatever Active directory account you want to run it under.
4) Restart SQL Server
This seems to have fixed the problem.