I figured it out! I had the same issue and nothing on this forum actually helped, so i figured, for the first time in my life, i would actually contribute. Go to the widgets section (where all the apps are, then at the top click widgets). Go to the Google Play Music widget, long press and drag up to App Info. click Disable, and it will ask if you want to go back to the factory default version, click yes. Voila! problem solved. It must have been some new update to the app/widget. I don't use the widget myself, so i'm not sure how this actually effects it's functionality. Good luck!