Hello, I've been searching for an answer to this for a few weeks. Finally figured it was time to ask. This seems to happen mainly with galleries:
You click on an image, the lightbox pops up - you see at the bottom of the lightbox "Image X of X" But, for some reason on some pages that "Total" number of images is off by one so the last image comes up with an error: This content failed to load.
You can see for yourself here: http://tsbcomplete.com/trianglex/hunting/.
Hope someone can help...