Check, does the green light of the memory card slot keep blinking? If this problem is happing with one card, have you tried other memory card? Because some time the problem cause due to faulty memory card so that I trying find out the exact problem. If not then I think there is fault in your camera and need to send it to repair. Before sending your cameras try to use different memory card. I hope the problem can be resolved. If you have deleted your pictures from old memory card then try photo recovery for Mac Software. You can easily remove your deleted and formatted pictures. Try to use brand memory card like CompactFlash card of Lexar with 1GB because there are some brands which does not work nice with D70.