I get this error message come up when I try to save a pic in Preview??

some thing to check, drag the photo in question to the desktop (it makes a copy) highlight it the press

COMMAND I

This will bring up the info window on it. CHeck the bottom under sharing and permissions and your name or admin and see if it has read&write permissions, if not you may have to enter your admin password to unlock the padlock and change ti to read& write. Also more towards the top make sure the box "locked" is not checked

Hope this helps