Whew! Glad that finally got sorted out. Just for the future, although I don't think you should try to do any more experimenting for quite a while, when a file shows the path beginning with / as in /Library/Preferences, that means it in the top level Library of the HD folder (the "root" folder.) The file that you trashed was not there, or in your User, which is sometimes indicated by the tilde ~ character, it was in the /System/Library/ and that's a very dangerous place to start trashing files from. (There are three Libraries, your User Library is hidden by default in Mountain Lion.) That's where all the necessary items for booting and many other highly critical things are located. Not to say it can't be dangerous to trash things from the other Libraries either, but that place is really a no-go unless you know what you're doing. Any time you are asked for your admin password when you want to move or trash a file, think twice, or three or four times.
The suggestion you tried, and got wrong, from that thread was to trash the com.apple.loginwindow.plist in /Library/Preferences, not in /System/Library/LaunchDaemons (a LaunchDameon is used at launch or startup, hence the startup problem.) If you had done that, then that file would have been automatically recreated on the next login. But, instead, you trashed a file which is necessary for startup and it's not a preference (preference files are usually where serttings are kept) file, even though it has the same .plist for the extension.
As for the other problem, I really can't begin to deal with that here. I would suggest posting a new topic for that one here in the Mountain Lion forum or in the Intel iMac forum, where this one started.
A word of advice now, don't go trashing any files until you have absolute confirmation from someone who knows what they're talking about.
USB can be very slow booting.
Message was edited by: WZZZ
