If you’ve ever tried to enable a guest account on OS X Lion there’s a good chance you broke something. The guest account is designed to create a temporary account on your machine that does not need a password and is removed after logout. The problem is that it has never worked for me. Even worse, it broke my System Preferences so I could not edit any users.
If you have ever enabled the guest account, on this screen:
Then you may be familiar with this error message when you try to manage your users.
To fix the problem select the magnifying glass (Spotlight) in the top right of the mac’s screen and search for “Terminal”. It will be found under Applications and when opened, you’ll have a white screen and a cursor:
Type, ‘open /System/Library/CoreServices/Directory\ Utility.app’ and press return (without the quotes). This will open up a new program, the Directory Utility. You may be prompted for your password.
You need to select “Directory Editor” and then search for users called “Guest User”. There may be a few users appear here with names like “Guest User1″, “Guest User2″, etc.Delete them all, leaving just the unnumbered “Guest User”.
Sorry, my Mac decided to stopped letting me reliably repeat this issue before I got the screen grab, but when you’re done deleting illusive Guest Accounts, it should look something like this:
And that should fix the preferences pain.
All in all Guest access to machines seems flakey, and I personally will be waiting for a patch before I try to enable this feature again.