If you have ever encrypted your phone whether through your curiosity, your paranoia, or your employer's paranoia, your Motorola (or generically Android?) Android smart phone did encrypt not only the phone's contents, but the contents of the SD card.
After you figure out that such encryption is an immense pain in the tuchus, you disable encryption on your phone. All is good you say, right? Well, mostly.
In fact, you'll do well until you decide to either do a hard reset of your phone or you move that (µ)SD card to a new Android device. Whereupon it will be telling you "SD card has been secured by another device and cannot be accessed unless formatted." You will enter what you remember your password to be and it will reject it, saying "Failed to verify SD card security settings. Encrypted content is not accessible." and then refuse to mount the SD for you.
Feeling desperate, you pull the card from your phone and insert it into your computer. Your files are there. Their contents are there. You ask yourself "What the fuck?!" Put it back into the phone. Same encryption key demand and rejection. Scratch your head. Google again. Find bupkes. Make a copy of the contents of the card. Format card. Restore contents of card. "SD card has been secured by another device…" Oho!
In fact, there is a hidden and very magic file sitting on the card named ".sds.bin" which is the flag to Android that the data on the card (may) be encrypted. If you remove this file (easiest on Linux or OSX) and then put the card back into your phone, you will be back in business. It seems as if someone at the Google forgot to remove this file when I told it to decrypt my phone earlier this year.