Mix_LoadMus hang

I’m finding that when trying to load music (OGG, MOD or even WAV) with Mix_LoadMus, my program hangs (and thus the emulator needs reloading) – does Mix_SetMusicCMD have to be used before loading music ?

Actually, it looks like Mix_PlayMus is causing the hang – it doesn’t happen with WAV’s, but it does with OGG and MOD files…