Glo MicroSD issues with glo

I've owned a Glo for about a year now, and I've started having odd problems with the microSD I use to store my books. Whenever I turn the Glo on, it gives me a "Can't recognize your SD card. Format to FAT32 & try again."
It then is able to read the contents of the SD--sort of: it takes ages and the Kobo freezes whenever I try to navigate more than a page at a time in a book, and sometimes it misses half the catalog (I have about 1000 books on it)
That's in spite of the SD card being formatted properly to FAT32 (I checked, it's not the SD contents--I reformatted it to empty FAT32 and I still get the same error message). I've tried resetting the Kobo to factory settings, updating to the latest firmware, but neither has worked.
Has anyone had this issue before? I'm inclined to think it's a Kobo issue (as opposed to an SD one), possibly with the microSD port itself, but I could be wrong...

Thanks in advance!