I have an SD card from a camera that my cousin tried in his computer and it worked initially, but then when he put it in later it says "please insert disk." I tried the card in both my mac and PC. The card won't mount on my mac, and it gives me the "please insert disk" message on my pc. If i put the card back in the camera, the camera will read no pictures. Any ideas or suggestions on how to recover the pictures on this card? The camera is a konica minolta dimage f300, and i have a lexar card reader with a san disk sd card.