are you sure they are actually plain old jpgs? Are they really on the server? I see nothing in your source that should not work. Typing in just your image link, I get a 404.
not to insult you, but we had a version of Photoshop in our labs that made two kinds of jpegs, real ones and these “special” jpegs (I can’t remember what they were for) that did not work on the web. It tripped up lots of users. Maybe try re-saving your image (make sure it’s a 72dpi jpeg – hi-res jpegs sometimes break in browsers too).