I went through multiple Droid Rezound models with this error. It was forcing encryption of the SD card for some reason. I did have the phone configured to pull my mail via exchange but our server policies did not require SD card encryption. I said fine, encrypted the card, then promptly forgot the password, especially since my mail policy did require a password for my phone. At the store, they tried my card in another phone, error. They tried another card in my phone, error. Gave me a new phone. A month later, happened again. I just made them give me another brand of phone for fear that an HTC would do the same thing, although my Incredible never had that problem, and I haven't had a problem with my Razr MAXX.