Solved! Go to Solution.
Actually, I'm finding that if I go to the url http://maps.sanbag.ca.gov/flexviewer/index.html then I will get the error. Going to just /flexviewer everything loads normally. I was only loading index.html at times so that I could add a config parameter to the url. Perhaps something is wrong with my index.html file. However, I'm finding that everything looks normal when I try maps.sanbag.ca.gov/flexviewer/default.htm instead of index.html. Default.htm was higher up the list in the default document priority.
So I guess everything is fixed, although I have no idea what was wrong with the index.html file.
I'm not sure how/where to tell flashbuilder to build an index.html instead of a default.html, but none of my projects even have a default.html, just the index.html.
You may try deleting your project from the server and re-export a release build again and see if it writes a correct index.html file without the "issue", especially since that is higher in the default document lists.