My card came unformatted. When I tried to format as FAT32 in windows using the card reader on my computer the phone would not allow the card to mount. After boot up the phone would say something like "SD card unexpectedly removed, please unmount the card before removing." I did unmount the old card before removing it. It would not allow me to mount, unmount, erase, or see the card capacity using the phone, although it worked fine in the PC.
I reformatted the SD card in my PCs card reader using the format utility from the SD Card Association and it solved the problem.
https://www.sdcard.org/downloads/formatter_3/
After reformatting I installed the new card into the phone, unmounted and erased the contents and then remounted and copied everything over from my old card (previously copied to the desktop). This is a cheapo ($30) no name via Amazon 32gb class 6 card, although I have my doubts about that class 6 rating.
After copying the 3gb of files over it gave me the same "SD card unexpectedly removed error" when I tried to play an MP3. Back in the PC all of the files had been copied over to the new card but I got an error in explorer that said something like insert first volume of multiple volume something or other. There was some 12MB .zip file that didn't look familiar but was also present on the old card. I deleted it with the PC and reinstalled the new card in the phone and now it appears to work ok.
Sorry for the long message, I just hadn't seen these exact issues in my searches.