On the mac, spotify often fails to play songs for me as well. The problem is an intersection of weird bugs and their lack of support for low volumes. When Spo

On the mac, spotify often fails to play songs for me as well. The problem is an intersection of weird bugs and their lack of support for low volumes. When Spotify plays an ad and you turn the volume down too low, they pause the ad and show a pie chart of time remaining in the gutter of the app near the repeat controls. They wait until you turn the volume up, where volume is the product of whole computer volume and their in-app volume control, to continue playing the ad. Now, if you are keeping the volume low, perhaps because you have in-ear earbuds and don't care to be deaf, there is a very confusing bug where an ad won't play at all, and in fact, won't even start playing so you don't see the time remaining pie chart. Instead, you get a yellow flash message that says, "Can't play track" or song or some such at the top. If you double click a track to play it, it just flashes the same message. The fix is to temporarily increase the volume above their minimum ad volume threshold and then hit the play button in the lower left corner of the app. This reliably fixes things for me. Snow leopard, macbook pro, spotify 0.6.1.287.g64b130c8