Mac Leopard not pulling up certain images in Shadowbox
I have just put up a new website to display an artist's gallery using Shadowbox (and Love It by the way). It works quickly and well on my Mac (Safari browser) and my two other computers (Internet Explorer), but I've received an email saying that certain images will not appear on somebody else's Mac (he's using Leopard).
One of the images that won't appear for him is the painting of a loaf of bread, and a peanut butter and jelly sandwich. This is in the second row and is the middle image.
What could be going wrong and how can I fix it? Thank you!