Hi - first post, and new to Mac after years with Windoze. I bought a used iMac, and started using and installing things, and then realised it'd be good to change the short name. I've followed the apple guide, (http://support.apple.com/kb/ht1428) but when I log in as root, rename the user directory to the new name and try to then create an account with a matching name, instead of getting the warning / override option the apple guide suggests, I instead get "Name is used by another user" in red, and no option to override. Any clues? Thanks in advance.