The link to the site is http://mbonwick.110mb.com/gallery
From reading what little information 110mb.com have made available, I understand that the HTTP referrer must either:
be 110mb.com
be site.110mb.com (where site is the user's site, in my case mbonwick.110mb.com)
or be non existant, through vopying and pasting a link.
Even so, I still can't see how this would affect zenphoto.
The only thing I see that is strange is that the "album" parameter has the slash(/) character encoded. This is not normal, it is usually left a slash. But I tried the URL with a slash instead of the %2F and still got the object not found.
Anyway, this error generally comes from not finding the particular album file or image file in the filesystem. So one possibility is that Zenphoto is no longer able to read the folders due to some permissions change. This might be what they did to prevent hotlinking.
At the suggestion of the host admins, I tried the gallery with the default theme again. This time it worked.
This has led me to believe that this is a template-related fault, but I've no idea what could have been changed/deleted in the "stopdesign" theme.
Thoughts please.
That should not be an issue, but maybe for completeness you should try the unmodified stopdesign theme. I checked the stopdesign theme from the nightly builds and it is not placint the %2F in place of slashes in the album urls.
Just FYI, this problem is typically caused by using the urlencode() function rather than the pathurlencode() function on album names.