Ok, I've had a pleasant experience with my imac so far, and it read my SD card fine at first. For some reason I put my SD in the SD card reader and copied the pictures from it. I take it out and put it back in my camera. "The SD card cannot be formatted. It may be defective." Really? I put it back in my iMac. It doesn't mount. I check Finder and Disk Utility. Ya, it's nowhere. I put my other SD card in my iMac. Same issue. Now my camera won't read that one either. I put them in my sister's $300 netbook running Windows 7 Starter. Funny! It reads them! However, my camera still doesn't and my imac still doesn't. I try formatting them. No go. I've tried every format I can. They are just dead. Useless. My sister's computer can read them, and even format them, but something in that stupid iMac made my SD cards defective. I can buy new ones, but should I have to? I can't even see if they'll work through the camera while connected via USB because the camera won't even read them. I bought a Mac to avoid ridiculous problems like this. Was I wrong? Is it just a ticking time bomb like every other computer on the market? Should I immediately go buy a backup drive? If it's doing crazy stuff like this out of the blue, how can I trust it not to randomly crash? I think I overestimated Apple's competence. This should never happen. It actually made my SD cards defective. I'm hysterical! I am completely dumbfounded! Everything else works fine. Should I run a virus scan? PLEASE HELP!!!