How close are you to a Sprint store? Maybe you can stick that card in another Touch & see if you have the same problem.

Also, did it ever work? or has it always been an issue? A hard reset test might be worth a shot. If you have too much too lose going that route, I would do a backup using SKTools. I've done successful back and restores with that program.

I haven't tried the latest release of Card Export yet, but all the other scenarios you described work fine with my 4GB SDHC card.