I'm trying to provide data files for my users to download.  I have an Excel VB program that generates all the data files and creates an HTML file that provides links to each of the files.  I then upload all the files and the HTML file to a DNN folder, and the HTML file is displayed as an Iframe.  These data files happened to be named xxx.GPX (GPSXML format files).  If I right click on a link shown in the Iframe, the file that gets downloaded contains a "file not found" error.  The files are where the link is pointing, and I can access them through the File Manager, but there must be something I don't understand going on.  The collection happens to include a PDF file, and that link works just fine.

The Iframe is viewable at http://www.chetcocyc.org/Activities/2009Activities/OceanMarks/tabid/774/Default.aspx

I'd be happy to use another solution if someone can suggest one.

I added the filetype to the Host Settings, and in file manger, I can open the files, so I'm pretty sure they're there.  I'm not sure I understand where to control the second suggestion "download is blocked by IIS". I've looked throughthe IIS properties on my server, and don't see anything likely. I don't have access to the live server's IIS so I need to be able to provide accurate instructions to the operator.