I have had this happen before. For me, it happened whenever music was played that I did not have.
I did a lot of research, and according to some Windows forums it appears to mean that your audio drivers became unresponsive. In order to stop the entire computer from crashing, Windows prevents the audio drivers from actually stopping, which prevents you from ending the program.
Check to make sure that your audio drivers are up-to-date. However, I can't remember how I actually fixed this, sorry.