At first I thought that the problem is on my side, but looked at you test gallery, it was the same thing. When viewing the full picture, it shows when page load, after a full load disappears. The same thing happens with the conclusion of album covers.
That is very weird, have you tried accessing it from a different computer to see if you get the same results? I can't replicate it on here or your site. I'd say it sounds like a browser/computer/network issue but since it's happening on mutliple browsers that are current so that knocks the browser out of the equation.