If you are trying to reference a file that is generated with a handler and you are instead getting the file not found message.
The handle is working fine in Visual Studio but fails to work when deployed to a webserver.
Have your hoster perform the following
In IIS you right click on your App, go to properties, click Virtual Directory Tab, Configuration, Mapping Tab, Add, point the Executable to c:\windows\microsoft.net\framework\v2.0.50727\aspnet_isapi.dll and add the appropriate Extension (“georss”) . I had to remove Script Engine and Verify that file exists check boxes and it worked.
this is where I found it. http://forums.asp.net/t/1408510.aspx