There was a software update yesterday, well I got it yesterday for my 520. Maybe that? Sorry I wish I had more of a solution for your. The 520 is getting a bit old now so I fear this type of issue will get worse. The 520 came out what 5-6 years ago now. My 500 was awesome until it het about 5 years old then it really went down hill. I guess its to be expected.
I am looking forward to upgrading when I need to. Can't wait for a bitter screen on the 1030 or whatever model that is.
Long story short try syncing to the computer and see if there is an update.