Conversation with Web Host Help Desk
Me (web designer): Hi. There's something strange going on with site because of your settings....(describes problem)...
Tech Support (them): Ok...hold on........(goes away for a few minutes)
Tech Support: OK. The problem is that you've got multiple files with the same name on the site.
Me: WTF are you talking about? We DON'T have files with identical names in the same folder anywhere on that site!
Tech Support: No, but you do have files with the same name in DIFFERENT folders. That is what is causing your problems.
Me: Uhhm...NO that's NOT causing the problem. That's a ridiculous hypothesis. Sites can have dozens/hundreds of files all called "index" or "default," as long as they are each in different folders.
Tech Support: Oh OK. Let me check something else then.
Me: Yes, please do that.