Okay, just as an interesting note, I commented out the conditional on admin-tags.php entirely:
`/* if (!($_zp_loggedin & ADMIN_RIGHTS)) { // prevent nefarious access to this page.
header('Location: ' . FULLWEBPATH . '/' . ZENFOLDER . '/admin.php?from=' . currentRelativeURL(__FILE__) );
exit();
} */`
and lo, the tags tab works and I get to the tag management window, but then all of the other tabs disappear except for "options"!
(When I click on that solitary options tab, I *do* go to the options window and get all of the tabs back like normal.)
So, for now, we can manage our tags and finish setting up this gallery, and hopefully next week we can track down the oddity, eh?