Cannot enable guest account I cannot enable Guest Account. Logged as admin, I got at Users &amp; Groups, select Guest User,and tick Allow guests to log on this computer. Even when ticked, "disabled" appears bellow Guest User account label. When I switch to the admin account and then back at guest account (within preferences) the box is now unchecked. Any ideas what can cause this?

p.s: I don't have FileVault

Update

So I thought to try a restart. A guest account is has appeared and working (looked disabled before restart) but I cannot open Users &amp; Group Prefs. When I select it I get: Could not load Users &amp; Groups Preference Pane.
As per David solution here (although not the cause):

I used Directory Utility (/System/Library/Core Services/Directory Utility) to delete two extra Guest accounts (&quot;Guest1&quot; and &quot;Guest2&quot;).
After deleting those two records I could open the Users &amp; Groups System Preference Pane.

Source: I've got &quot;Preference Error: Could not load Users