Bit of a worry this one...
Just dropped my CF card (sandisk extreme 4, 4 gig..) into the reader to upload some images and nothing shows up on the computer (nothing even shows in Finder)
Tried the card reader in different ports on the laptop, no avail...
Change CF card and lo, that shows up on the system....
I've then inserted the 'dodgy' card into the camera and it shows 'folder contains no images' = PANIC!!
However, there must be info on there as 'frames remaining count' is on 111, the empty card would show 192.....
Tried a few shots on the card, no problems, they show up fine on the camera (as they did yesterday...)
Any suggestions whilst I dig out the 'data recovery' disk.......

