I've had this problem too, ever since 2.0 came out. I bought the game via Steam, if that matters, and whenever I retry a level in Time Trials with the Enter key, the music disappears.
Another bug, quite separate from the music, is that my time trial scores are no longer saved when I exit the game. I restart the game, and my trophies are still in place, but in the TT menu, for each level, it says "Not yet attempted". When I go back and complete a previously-completed TT, my best rank still appears, but my high scores are corrupted somehow:
I guess these bugs don't matter too much, but it would be nice to see them addressed or fixed.
