Failure to connect to server cannot generate SSPI context

Hey guys,
I am running a SQL Server and Windows 2003 server computers both on the same server computer.
I was trying to log in using windows authentication and the OS loads fine then I get this error message:
Connect to Server
Cannot connect to MS SQL.
Additional information:
Cannot generate SSIP context. (Microsoft SQL Server)

OK
Any help guys?
Thanks.
