The image host isn't the issue. The fact that the URLS have spaces (or %20) in them is the issue. Try reuploading them with a different name. This is a known issue in the image proxy we have.
Really great work here, although a lot of people are unlikely to use a desktop background that has a name/logo on it. Not that I in anyway disagree that you should put one there, I most likely would. But apart from that great work.
