I frequently encounter a problem with my music at work.
I use a Mac with one of those little Apple keyboards. It has buttons that control iTunes, play, pause, and so on. I use it to pause my music when something is happening in the studio that needs focus. Then, when I come back, I can start the music back up with the keyboard again.
When listening to Pandora, however, I completely forget about this. Something comes up that needs focus, so I hit pause on the keyboard. This time, that key causes iTunes to start playing right over Pandora. Both, at the same time. Leaving me completely distracted, and my focus in tatters.
Really wish Pandora was able to take over those keys when it was running.