User Account Dissapeared and Accounts Preference won't load

I have OS 10.4.10 on a 15" Macboook Pro that's about a month old. It's my second MBP. This afternoon I went to use an account that I use quite often to do my music stuff. The account had disappeared from the machine! The user is not in the 'switch users' drop down off the right top menu next to spotlight icon. I can't login from the login panel either.

The files were still there (phew!) and I copied the whole user's directory onto a backup disk. Being familiar with Unix systems, I get a terminal open and look at the user's directory in /Users I can see that that the directory permissions have reverted to a numeric ID rather than the user's name. The group id is OK though (i.e. not numeric).

So thinking that I could perhaps just recreate the user and copy all the files back into the new user's directory or something, I tried to run the Accounts system preference and see what I could salvage. But the accounts system preference panel is blank!

I rebooted a couple of times, tried again, this situation continued. OK the Accounts subsystem or whatever is obviously totally hosed. So I thought lets try to reinstall the system and Accounts system should be reinstalled, right?

I dragged the system disks out, rebooted, checked the disk (all OK), and re-installed the operating system. Obviously not a clean install. Two hours later (groan) and all is over, you beauty I think, log back in, go to run the Account system preference panel ... the situation continues!

What can I do now? Has anyone got any good ideas? I am desperate!

thanks
scot

When I try to open the Account preference, the console.log has the following


2007-09-01 18:53:09.873 System Preferences[896] *** NSRunLoop ignoring exception '*** -[NSCFArray addObject:]: attempt to insert nil' that raised during posting of delayed perform with target 3553a0 and selector 'setCurrentPreference:'
2007-09-01 18:53:17.828 System Preferences[896] _initWithWindowNumber: error creating graphics ctxt object for ctxt:55047, window:0
2007-09-01 18:53:17.828 System Preferences[896] CGPixelAccessLock failed!
Sep 1 18:53:17 CrazyMcphee-2 /Applications/System Preferences.app/Contents/MacOS/System Preferences: Failed to create window context device
Sep 1 18:53:17 CrazyMcphee-2 /Applications/System Preferences.app/Contents/MacOS/System Preferences: CGWindowContextCreate: failed to create software delegate.
2007-09-01 18:53:22.996 System Preferences[896] *** NSRunLoop ignoring exception '*** -[NSCFArray addObject:]: attempt to insert nil' that raised during posting of delayed perform with target 3553a0 and selector 'setCurrentPreference:'

For anyone who hits this same problem in the future.

The answer is to restore the netinfo database. I didn't have a (non-corrupted) backup, so I reinitialised it to default, did the first-time set up again, then when I added the accounts with identical unix user names as before and pointed them at the old user directories, the Mac was perfectly happy to re-use the existing user directories.

Restoring netinfo db is detailed here: http://docs.info.apple.com/article.html?artnum=107210
(I used option III in that document)

Additional details found in this thread below. This has some people who had the same problem caused by usernames in the netinfo db with invalid data, which can simply be deleted from netinfo with teh netinfo manager App in Accessories. This easy fix however did not fix my problem, as I didn't have any invalid user Ids. I had to re-initialise the netinfo db):
http://forums.macosxhints.com/showthread.php?t=41871

Another page discussing recovery of netinfo database:
http://www.westwind.com/reference/OS-X/NetInfo-recover.html

Resetting the netinfo defaults worked

Thanks for that. I'd lost my user account after trying to recover a damaged system. My old Pismo kept generating a kernal panic when I tried to boot with the Tiger 10.4.11 system. Other partitions with 10.3.9 worked, and 9.2 on the main partitiion worked, but 10.4.11 seemed irrepairable.

In the end I tried updating the files from a virgin 10.4.11 partition in the hope of resurrecting the System with all its installed apps intact. But I wouldn't recommend this before backing up all user data!

The process, using SuperDuper "Copy different files", worked, and I finally managed to boot the Pismo with 10.4.11, but although the user account info was still all there, no user accounts were showing at startup.

Resetting the netinfo defaults, and removing the AppleSetupDone file allowed me to reinstate the account using the original account name and shortname, as you did.