Can't install anything - user name field blank
Recently when I try to install anything that needs my permission, the username field and password fields are blank. It is usually auto-filled. I can't unlock the padlock. I was trying a combo update of El Capitan hoping a clean install would fix it but I need my username to do that.
I thought the username was what is in this box below from Users and Groups (greyed out for privacy) but when I type that in the box wiggles and rejects it.
I know my password is correct because I reset it in Terminal and it was successful. Is there a plist file in Library that could be corrupted?
Any help greatly appreciated.
Dave B
iMac, OS X El Capitan (10.11.2), 27 iMac i3 12GB, two 15 in RetMBPs,