I've purchased two different 128 GB msd cards one a San Disk from Amazon, the other a Gigastone from Best Buy. The San Disk stops working the way I need it to after so much is put on it, and I've just decided to buy another one and send it back. But now I'm having trouble with the Gigastone. It was working great until I moved one little file onto it, and now I can't do anything with it. It appears to operate like a working card...I can stick it in my 3DS and all my games work. But the thing is, anything I try to add to it gets deleted the next time the card is accessed, and anything I try to delete COMES BACK! It's like it's write protected, but doesn't behave like a write protected card. I can rename things, move them, copy them, whatever, but when I take it out and put it back in, everything is the way it was before I made the changes. I've tried formatting it multiple times with various methods and programs, but it never sticks. Any idea what I should do?