I have a IIS7/ASP.NET application running with the following configuration: Anonymous authentication (IUSR). Application Pool running as a domain account If IUSR is denied the "logon locally", then it appears that ASPX pages will still render their HTML, but static content such as images will not be delivered. I'm wondering what the technical reason is for this? If IUSR is "broken", why will a request to an ASPX page be passed down the pipeline and executed, but IIS will refuse to serve an image in the same directory?