How do I stop my victory theme from looping?

I replaced it with an MP3... But now for whatever reason it loops.

Does anyone know how to make it play only once?

I'm pretty sure the songs loop regardless. Maybe the previous song you had just had a long part with silence at the end, so if you really want, you could just add some silence at the end of the song and it'll seem like it stopped, at least for a little while.

That would make sence I think... I'll look into it or find something that does loop.

You can easily add silence using audacity.

...or use Disharmony, which has a "Loop Editor" for MP3 and MIDI files.