It works fine in Firefox 11 but not in IE and Chrome. By default, IIS6 does not serve .json (no wildcard
MIME type). So you will see a 404 not found thrown.
By default, IIS in Windows Server 2003 and beyond does not serve files that aren’t of a MIME type that it knows about (instead returning 404 errors).
So, to serve up JSON files you need to add a MIME type to IIS to allow it to serve that type of file. You can set it at the site level or at the server level.