404 : file not found" error.
This is a result of the upgraded security functionality of Internet Information Server 6.0 and carried into 7. Enhanced security does not allow for the access of any files under a folder path that particularly are of type 'config'.
To prevent disclosure of configuration information, IIS is configured to return the generic 404 custom error page by default on this denial. To resolve this error, use IIS manager to add the file extension to the Multipurpose Internet Mail Exchange (MIME) map on a specific directory or Web site.
Here is a link to a Microsoft TechNet article:
Notification Server 6.0 with IIS 6.0
SMP 7.0 with IIS 6.0
SMP 7.1 with IIS 7