The card type or brand is not only a question of speed.
I bought a 256 MB SanDisk card for my *istDs that worked well in the camera but was impossible to read from my puter, not even when I attached the camera directly to my Mac.
A 64 MB Kingston card that I had in my Optio worked fine, however, so I assumed the SanDisk card was faulty and had it replaced. Same problem with the new card, though.
Next, I got a new card reader and that setup worked for a month or so with the SanDisk card, after which I was back at square one.
Finally, I bought a 256 MB Kingston card that has worked fine ever since.
Bertil
