I'm experiencing a truly strange and frustrating phenomenon with images not displaying. I'm convinced that this might be a server-side configuration issue, and I've opened a support ticket at my hosting company (HostGator). Meanwhile, I thought I'd see if some Drupal experts might offer me some input that I could pass along to the HostGator support team.

Here's my issue...

I've got three domains, add-on domains specifically, each residing in their own folder (no multi-domain setup here).

ONE of the domains is showing all icons and images the way it should
http://HesitantRhino.com

TWO other domains with identical add-in modules installed are NOT displaying any of the icons that should be present, not in any web browser. Here are the domains (and naturally, according to Murphy's Law, these are works in progress for paying clients - SIGH)...

http://GodIsHolyAndAwesome.com
http://WellnessMinister.com

Here are the add-on modules that are not behaving as expected...
Views - (no plus-sign icons on the configuration screens)
External Links - (no external link or email icons)
Service Links - (no icons for the various services)
Google Maps Tools - (no flags displaying on the maps)
Gravatar Integration - (no user avatars displaying at all)

Anybody see a pattern here?

Now to throw something else into the mix... HostGator had previously added some white-list rules to Apache's mod_security for the domain that IS working (HesitantRhino.com) because ANOTHER CMS (Moodle) was also not displaying images in certain instances (the pop-up image browser for the HTML editor).

Any ideas on where to turn to resolve this issue, or even a step-by-step checklist, would be most gratefully appreciated. Also feel free to get in touch via private message on my contact form if you like.

Thanks!
Klaus