This question snuck by me.
Did you ever figure this out?
My first guess is always to blame the memory card -- especially if it's an SD card. The lifespan of an SD is horrible, and that format needs to go. It's way too touchy when it comes to static electricity especially. I've seen far too many dead SDs in my day. I hate having to remove one of those, and only do so in the studio, so that I can go directly from the camera/phone to the card reader. In fact, just plugging the device into USB, and not even removing an SD at all is my first choice!
Also, what brand is card was this?
Quite a few brands are just garbage, and that includes better flash memory formats like CompactFlash (as used in pro cameras). These days, I mostly prefer Transcend to anything else.
