A:AnswerI'm encountering the same problem with my iMac. I suspect that something's wrong with the DC5v port, because the USB cables I'm using work with other units, like my camera. I'm thinking about somehow accessing the SD card another way...possibly with the camera?
A:AnswerTry formatting the card with the camera. I transferred a bunch of files from the camera to my laptop and got this message. A quick format fixed it.