SD card says it is mounted, then says it is unmounted without doing any thing. how come?

[shylow]

I have been having problems with my SD card it was mounted then all of a sudden today all my pictures got erased, and when I go to settings and tap storage it says: settings had stopped unfortunately. And said my SD card is um mounted. What is going on?

 

[pjbeee]

A known issue with the S4, I'm having this issue repeatedly as the SD card gets more data (usually pictures). Phone starts unmounting and remounting SD card and overheats, using lots of battery. And even with latest snapshot (M9) of Cyanogenmod 11 (4.4.x). Haven't lost any files yet though. Have found no definitive solution. What usually works for awhile is to remove the card, copy everything off it, reformat the card, and then only put back the pictures you'd like to show around, and re-insert in phone. I have a more-or-less generic Class 10 16GB card, but there are postings that say a genuine Samsung card helps.