I have an 21.5" iMac (Intel) which runs OS 10.6.8, its SD card reader does not WRITE. It says read-only in info. I used other SD cards to try - all the same. It used to write before, few months ago, it stopped writing - no deleting, no adding in anything I opened Disk Utility, its erase, repair ... etc functions are all disabled - so I cannot format it. So I used used an external (USB) card reader to try, it works perfectly fine with reading and WRITING Disk Utility also works fine with the SD cards which are connected through the externer card reader. What is wrong with the 21.5" Intel iMac's SD card reader? What can I do...??? Many thanks! Priscilla PS: I recognise that many people have the same problem. I also called Mac and they guided me to do a PRAM reset. It still does not help......!!! I am getting quite frustrated.