@andysams: I'm sorry to hear that you're experiencing this issue. Which music app are you using, and are you streaming your music via a mobile data connection? Streaming apps are power intensive and cause your phone to overheat after periods of prolonged use. This, coupled with the recent warm weather, may be what's causing the app to close down. If you have a case or cover on the phone, try removing it to see if you notice an improvement, and keep the device out of direct sunlight where possible.