Before we say the phone or the sd cards are bad I'll start by saying this is my 3rd new s5 and I've tried two new 64gb sd cards and same problem. Ok I've encountered a problem where my phone will delete pic's and songs from my sd card when I reboot or power the phone off. A lot of times when I take pics it ends up with gray lines in it or is blacked out with a lighting bolt threw it. I've reformatted both sd cards with various formats including formating them with the phone. The brand of sd cards are Samsung Evo and Sandisk, both class 10. I put in the same brand 32gb sd and its working fine. Anyone know whats up with the 64gb cards since the phone is capable of 128gb? 4.4.2 and 4.4.4 both giving the same problem.