It must be a pretty bizarre bug, then, because I can't think what could possibly cause something like that to happen.
It wasn't unheard of for certain sites to fuck over users of certain browsers, at least a few years ago, and Photobucket seem like pricks, so I wouldn't put it past them to do something like that.
It annoys me when sites cripple themselves on certain browsers for absolutely no good reason (e.g. YouTube not using HTML5 for all videos with Opera on *nix, even though it can support any format/codec that YouTube can serve, if GStreamer and FFmpeg are installed).