Originally Posted by m3incorp
It could just be that your phone has issues or you bought one of the many FAKE SanDisk cards. Always buy SanDisk cards from reputable dealers. What makes you say Samsung phones vs your Samsung phone? You are the very first person I've heard of any phone having an issue just because of the Class of a memory card. I've used Class 10 cards in every device that I own that accepts an SD or MicroSD card and never had a card failure. I've had a SanDisk 32GB Utra in my Samsung Galaxy S4 from the day I bought it. I'd do a little research on exactly what the "class of cards mean".
Also many people are saying buy the fastest speed out there. The device you are using the card in determines just how much of that speed you can use. If a device can only transfer to or from the card at a particular speed, as is the case with all devices, then it does no good to buy a card faster than your device, just for the sake of buying a fast card. I'm a long time photographer and many people use to say the same about the memory cards you buy for your camera. You can now look up how fast your camera transfers, and base your card speed on that. Now with that having been said, I buy Class 10 cards, as the cost difference is not that much.
There is a quite exhaustive thread on the S3 forum, currently third page I believe, about SD cards being disabled by that phone. Different brands and speeds. His statement is not the first I've heard of that and in fact, I just got rid of my S3 and moved up to the S4 and was having some issues with the card in my S3 as well. Having said that, I don't think it was the card, but they phone having issues. Although, in reading through that thread, there were some statements regarding replacement cards from SanDisk I believe that were acknowledged as being in a bad batch of cards, specifically certain size and speed, if I'm not mistaken. My card is a Samsung 16 gig card that came with my old memorize. Lol. It is now housed in its 4th phone and luckily no longer in the S3 where I was becoming afraid it my die.