It's fixed.
Now, the problem wasn't at all what I thought it might have been. No. What it was is that two lines of code, the ones that display the buttons to switch captures/descriptions, were completely missing from the routine that runs that slideshow. And what's even weirder is that they weren't even two consecutive lines of code because they're separated by three other lines. Just how those two lines disappeared is a complete mystery to me. Lines of code, particularly non-consecutive lines of code, should not just up and disappear!! But then, as Midnite and I have often said, sometimes it's as if this place is haunted. And as such, I've given up trying to fathom how these things happen.
But things are working again - and that's all that matters...
And thank you, Gerard, for pointing the problem out because sometimes weeks go by without me checking out that particular slideshow.