Cannot generate SSPI context

How to troubleshoot the "Cannot generate SSPI context" error message
http://support.microsoft.com/kb/811889

Usually this drills down to improper SPN [Service principal Name] Not registered properly

Related Knowledge Base Articles
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Troubleshooting Kerberos Errors
http://www.microsoft.com/technet/prodtechnol/windowsserver2003/technologies/security/tkerberr.mspx

How to enable Kerberos event logging
http://support.microsoft.com/kb/262177

How to troubleshoot the "Cannot generate SSPI context" error message
http://support.microsoft.com/kb/811889

How to make sure that you are using Kerberos authentication when you create a
remote connection to an instance of SQL Server 2005
http://support.microsoft.com/kb/909801/en-us

Security Account Delegation
http://msdn2.microsoft.com/en-us/library/aa905162(SQL.80).aspx

SQL Linked Server Query failed with “Login failed for user …”
http://blogs.msdn.com/sql_protocols/archive/2006/08/10/694657.aspx

Windows 2000 Resource Kit Tool : Setspn.exe
http://www.microsoft.com/downloads/details.aspx?FamilyID=5fd831fd-ab77-46a3-9cfe-ff01d29e5c46&displaylang=en

Windows Server 2003 Service Pack 2 32-bit Support Tools
http://www.microsoft.com/downloads/details.aspx?FamilyID=96a35011-fd83-419d-939b-9a772ea2df90&DisplayLang=en