Currently Being ModeratedJul 26, 2011 4:29 AM (in response to masa T)
I have exactly the same problem. I updated Snow Leopard to Lion on a MacBook Pro, and enabled the Guest account just for sharing. Then I saw the login icon on the menu bar, which I didn't add, so went to the System Preferences to access Users & Groups but I get the same error.
Any help appreciated.
Currently Being ModeratedJul 26, 2011 5:24 AM (in response to larosa)
I can log in as guest (user = guest, no pass), and from there I can access the Users & Groups preferences for that account. In the worst case, from there I could create a new admin account and then remove my previous one. However I would like to avoid that...
Currently Being ModeratedJul 29, 2011 12:11 AM (in response to masa T)
I tried to create a new admin account, but then once logged in with that account, I tried to open Users & Groups but nothing: still the same error. It seems I can only access that panel from the Guest account...
Anyone out there with the same problem? (or better with a solution to it...)
Currently Being ModeratedJul 31, 2011 9:53 PM (in response to masa T)
Sounds like you have a badly corrupt preference file. I had the same problem and the only thing that cleared it up for me was a complete reinstall of Lion. Sorry to give you this bad news but that was the only way to fix it for me. No matter what I tried, the pesky file wreaked havok on several things in the system.
Currently Being ModeratedJul 31, 2011 11:26 PM (in response to Nikoman)
This happened to me just after I clean installed the Lion and I didn't want to spend too much on finding out what's wrong, I just re-installed it...
Currently Being ModeratedAug 1, 2011 12:51 AM (in response to masa T)
Thanks for the reply. It seems to be a problem with Lion then (it even happens with clean installations). Well, no doubts Lion would be immature. I should have waited for the first "service pack" before installing it...
Currently Being ModeratedAug 1, 2011 9:14 AM (in response to larosa)
Did you make sure you had all the latest updates to Snow Leopard before you started? Did you verify/repair disk permissions? Does your Disk Utiliy work? Mine didn't work during the troubled times, the system prefs and that were hosed.
I still have smooth sailing since the last reinstall of Lion.
Currently Being ModeratedAug 1, 2011 11:07 PM (in response to Nikoman)
Yes, made sure all required software was there before updating to Lion. Also, I've checked and DiskUtility works file. I just repeared some disk permissions but sitll the Users preference pane doesn't open up.
@MasaT: now that you have reinstalled Lion, have you tried to enable the Guest account and see if your Users pane works?
Currently Being ModeratedAug 1, 2011 11:19 PM (in response to larosa)
I have one more iMac to install Lion. I will try enabling Guest account after clean installation..., but I think it's worth reporting this to apple support..
Currently Being ModeratedAug 2, 2011 6:43 PM (in response to masa T)
I am experiencing the same error.
I was running OS X 10.6.8 (with the supplement 10.6.8 v1.1). I regularly repair permissions, once a month or so. Other control panels seem to work, just not this one.
Oddly, the Parental Controls pref pane shows "Guest account" and "Guest account1". These would seem to give a little bit of credibility to the idea that something is messed up with the guest account after upgrading to Lion. Also, neither guest account could be deleted from the Parental Controls pref pane, even though there is a minus button which ostensibly allows you to do that. I get a confirmation, "Are you sure you want to delete the user account "Guest Account"? The user account "Guest Account" will be deleted permanently." But if I click OK, nothing happens. Same for both guest accounts.
Currently Being ModeratedAug 2, 2011 7:04 PM (in response to Michael Prewitt)
Yes, same problem here. I have two Guest accounts while I only enabled one.
Currently Being ModeratedAug 7, 2011 1:46 PM (in response to masa T)
I used Directory Utility (/System/Library/Core Services/Directory Utility) to delete two extra Guest accounts ("Guest1" and "Guest2").
After deleting those two records I could open the Users & Groups System Preference Pane.
Currently Being ModeratedAug 7, 2011 2:00 PM (in response to David L. Huxtable)
Thanks, David. That worked for me too.
Currently Being ModeratedAug 7, 2011 3:30 PM (in response to David L. Huxtable)
Thanks David, that also worked for me.