Having a recurrent Card Err! on your camera memory card? We tried a couple of ideas and this really sorted it.
1) Camera chooses not to be able to read the card it did two minutes ago. Solution: clean it. First clean the card slot by wiggle a few cm of Velcro hooks. The gritty surface helps. Next buff up the contacts of the Smart Media card - use a cloth and a few drops of brass/silver polish. Try, I hope it works for you.
2) Deleted some pictures on the card you thought were not worth keeping two minutes ago. Solution: You need a half decent unerase prgram. Get that from PC Inspector (CONVAR) - Google for this. It costs a very generous nothing. Heed all warnings about unerasing files of the hard disc (it can do this too - but there are reasons to be careful).