I have had this problem too in addition: (I sent card into Sandisk and supposedly they sent me a new one OR not?)
Using a Sony A77v (I avoid trying to use this 64g card)… (in red) err in the viewfinder… sometimes and repeated reformatting leads to camera shutdown OR the camera has shut down from the start.
Also when a successful reformat works on this 64g fast card followed by successful image capture - putting this card into a MacPro or MacBook pro, OS 10.8.5 sometimes reveals:
red warning ! Mac OS X can’t repair the disk “Untitled.”
You can still open or copy files on the disk, but you can’t save changes to files on the disk. Back up the disk and reformat it as soon as you can.
For one, I reformat cards in the a77v camera or whatever camera after everytime I download images. Several times, only from the a77v after getting this red error warning - I have not been able to download the images and lost the shoot or the .ARW files are corrupted.
a77 Ver. 1.07