Only other thought is that this kind of thing happened to me once with ad-blocking software. If you're on a PC you should do a search for your 'hosts' file; it won't have an extension usually, but you can open it with a basic text editor. If it has a bunch of URLs in there and Renderosity is one of them, that's your answer. Cancel it out and resave. If it appears again, then some software on your computer has a grudge against Renderosity!