If this is happening check if there's a duplicate MIME map for the given files. Select the site in IIS 7 manager and click mime types. If there's an error, it'll give a message or else add the mime type if missing.
When there is a + sign in the path section url, the IIS 7 sends an HTTP 404 error. ex: tipila.com/tips/a+b Add the following to resolve the issue, to root web.config <system.webServer> <security> <requestFiltering allowDoubleEscaping="true" /> </security> </system.webserver> Note however replacing space with a + sign i ...