I unplugged my Cybook from the computer without first unmounting the volume. It was still in the process of deleting a few files. When I turned it on the files showed in the library but were unable to be viewed. After I plugged the Cybook back into the computer the file system was mounted as read only and dmesg spit out a large number of IO errors.
The Cybook’s file system was damaged. Thankfully the Cybook uses Fat32. All that was needed to fix the errors was to run the following:
sudo fsck.vfat /dev/sdb -artvVw
/dev/sdb is the device id for the Cybook’s memory. If you are unsure of what it is, plug in the Cybook, wait for it to be detected and run dmesg in the console. At the end of the output there will be information about the device being connected and what device id the system has assigned to it.