Don't use that card anymore. That issue could have happened any where in the chain of data, from dumping to buffer, writing to card, reading from card, writing to your disc for editing. You can try and pull those images from another reader onto another disc maybe. But, odds are, that's an issue with the memory card itself. Replace it and don't use it, especially if you are being paid to shoot weddings. As someone else mentioned, warranty may apply, its worth looking into. But cards are so cheap for good ones, you should have several anyways without question.