Music Starts Playing Randomly
There is most definitely a solution. Go into Gmail and find out what your notification sound is set to. I had to bring up the gmail app, go into settings, select each account, go to Labels to Notify, select Inbox, and change the ringtone. My problem started after I went through and set all my notification sounds with sounds downloaded from Zedge then loaded new MP3s onto my phone a couple days later. The gmail notification sounds got changed to one of the new songs I just copied to my phone.
Also, I had to change my text message notification sound through the messaging app.