Hallo sponder, in fact my problem started when I was copying a pdf file to Cybook, both computer and Cybook suddently froze. Then I forced them to shut down. When restarted, the computer could never recognize my little friend again.
The copied pdf file could be found on Cybook, but cannot be read because of error. Other books show normally.
As for the freezing problem I mentioned in Floor #3, it has been solved. Reset did not help in page flipping, however, after reset I could turn off the machine. Then restarted, everything seems fine again, except for communication with computer. I hope I could have the chance to run chkdsk on such an invisible device. Still thank you for sharing your experience.
By the way I don't use a SD card.