^^^ that happened on my Dink A LOT! Like above said transfer all you can to your computer. Then reformat your card. The cause could be a corrupt file, be it album art, mp3 or a new app that isn't playing well. I had a pix say app that did it for me once. But I also had a 16gig card filled with music and art work. I found that once everything is off your card, there maybe something that just won't delete. That will be your culprit. Sometimes its very hard to get rid of without a special program. Or some good computer knowledge . What worked for me was renaming the bad file. Best of luck unmounted SD drives me nuts. expescially now that I have a 32 gig card filled with music .