IIS 7.5 configuration issues

Question

I have been struggling trying to get an asp.net app, developed in VS 2010, Csharp, .Net 4.0, ... And windows authentication to play well on server 2008, running IIS 7.5. Anonymous is off, Direct is on, and the service account set up for this web app is designated as the app pool identity, with integrated as the pipeline setting. My problem occurs after authentication has successfully occurred, when a link is selected that causes the app to retrieve an image file from a file server in the same domain, the darn windows authentication dialog box comes up again and this shouldn't be happening. The directory folder that contains the images has the service account added to it's security with full access. On my local box, all this works seamless. I need somebody to give me some information on what might be missing for config settings or options turned on/off in IIS 7.5. Can anyone help me out here??? Thanks, SMA