The last two times this happened to me, I got an update from Microsoft a day or two later; Anniversary update and then a big camera update. Mine was acting up this morning, but I put it off to an email with some embedded elements that are bringing my phone to a stop.
I did a soft reset (hold power & volume down for 10 seconds - will reboot) and that fixed it both times.
Microsoft needs to manage its OS updates in the background better. Any other app updates without issue through the store.