|It sounds like the cards are write-protected. This may help:|
With my cell phone, if I remove the micro SD card and put it in a card reader to copy off pictures, the OS will treat the card as if it's write protected--can't add or delete files. But when it's in the phone it'll function properly. It wouldn't surprise me if that was typically the way cameras and phones set up their cards.
Real men don't use AntiVirus; they just reformat