Maybe you faded it out somewhere? Try setting the volume in the <<audio>> call.
<<audio "mainmenumusic" volume 1 play>>
I don't think you need so many <<first>> macros there either. Instead of switching back and forth, you can do:
<<first>>First visit content and links.<<finally>>Second visit content and links.<</first>>
Also, if you're gonna use a <<nobr>> you can/should space out your code to make it more readable.