I've been editing this one in Audacity to try and remove any silent periods at the beginning and end.
I used Sony Acid Pro 6 to make this file, and it loops in the program.
Why it doesn't loop outside of it, I don't know.
I can render it as .ogg, .wma. .mp3, .wav, and several other uncommon formats, so I'm not sure which one is the best for looping.