A wild uneducated guess. Could you have formatted the first card using the computer?
There are a few posts in
www.DPReview.net that say that formatting the card in the computer rather than the camera has caused problems. Something about FAT32 formatting rather than FAT, from the computer being the problem.
There have been suggestions that formatting the card in the camera can correct the problem. You could try a search in DPReview or ask your question in the Minolta Forum . There are a lot of very knowlegable people there. Good luck.