3 small notes: This only started occurring after the 2.0 update, usually while traveling between places. The music sometimes doesn't stop playing, even while the computer is closed. Also, a technical detail is that i'm usually playing in a room-tempurature place with my fan running and windows open, so it's a reasonable temperature and decent airflow.
As a temporary fix, I find that closing and opening my laptop forces it to become unfrozen (I close it, I open it, it stays frozen, the screen goes black like going to sleep, and then it turns on and is unfrozen). This is probably just a sign that my computer is really slow, but that's pretty much all the details and this is a fairly recent problem.