My MicroSD card started ejecting about a month ago in my S3. Not physically, just the software. It will read the card, then say it was removed, then read it again. Every once in a while it will say the SD card is corrupted. I bought a new one and put it in and got the same result. I physically ejected the so it wouldnt kill the battery. When i push it back in sometimes I can go a whole day before it starts doing it again, other times not even 5 minutes. Has anybody else had this problem? I've owned it since the day it was released.
Sounds like a defect. SD card failures are pretty common but the likelihood of two in a row is low. I would exchange the phone or send it in, for warranty repair. Rogers will take it right at the store.
I have NEVER seen this happen on my 2GB / 8GB 16GB & my 64GB micro SD card. I switch them from different phones & on my S3 as well. Never had this issue. It could be the device is either doing this or the memory card is not made for the device. I would contact Samsung & see what they say.