My Imac is reading the SD card, however when I right click to copy into it the option is not on the drop down list. The SD card is working on other machines, this has never happened before. I am using a card reader.

Actually, the Mac IS LETTING YOU. The problem is with the card. It is formatted NTFS. You need to install NTFS-3G or SL-NTFS.

Also, don't right-click to copy. That is a Windows method. Not saying it won't work, but test it with a drag instead. To drag, select a file and while holding down the click, move the file to the flash media icon.

Well, to be truthful, no inanimate object like a card or a computer does any letting or not letting. That would involve holding your arms behind your back. They can't really do that. The thing they do is.... nothing. They do not respond.

any password activated ?