Stuck at login screen after update froze

Question

Hi everyone, I have a Macbook that is a couple years old and have Leopard on it. Last night, I was prompted to install several updates and then restart my Macbook. I did so and then the updates began to install, but then appeared to stall. I hit the power off button and then turned my Macbook back on again. This brought me to the login screen, but I don't have my Macbook set to require me to login each time I use it. I entered my password and then it went to the blue screen like it was about to bring me to the desktop. But that didn't happen. It brought me back to the login screen, which is where I am still stuck as of this writing. Is there anything I can do? Thanks for your help.

Answer 1

No guarantee this will solve your problem, but you can give it a try:
You will need to type some Unix commands. If you are not comfortable with this, I don't know of anything other than a re-install. But if you are careful, you should be OK. I recommend you print this out in a largish mono-spaced font so you don't miss any spaces (or add extra ones). Note that case is important.
Be careful. Some of these commands are dangerous, since you are going to be root.
Start up in Single-User mode by holding down the command (Apple) key and the 's' key while you press the power switch. You can let go the keys when you see white text on a black background. When this has finished you will see a prompt ending in '#', although there may be other messages. Type
/sbin/fsck -fy
followed by a return, at the prompt and wait a few seconds for 8-10 lines of output. If the last line says repairs were carried out, repeat this command until you get a message 'The volume <yourdiskname> appears to be OK'. Then continue with
/sbin/mount -uw /
cd /Library/Preferences
rm com.apple.loginwindow.plist
rm com.apple.windowserver.plist
cd /Library/Caches
rm -r *
cd /System/Library
rm Extensions.kextcache
cd /System/Library/Caches
rm -r *
reboot
This should now take you to a proper login screen after the normal boot sequence. You should then Repair Permissions by using Disk Utility (in your /Applications/Utilities folder).
If you get error messages saying files do not exist, just ignore them and type reboot.
If the above is unsuccessful then you may be able to reinstall OS X using an Archive and Install which does not erase the hard drive:
How to Perform an Archive and Install
1. Be sure to use Disk Utility first to repair the disk before performing the Archive and Install.
Repairing the Hard Drive and Permissions
Boot from your OS X Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Installer menu (Utilities menu for Tiger.) After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported, then quit DU and return to the installer.
If DU reports errors it cannot fix, then you will need Disk Warrior (4.0 for Tiger) and/or TechTool Pro (4.5.2 for Tiger) to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.
2. Do not proceed with an Archive and Install if DU reports errors it cannot fix. In that case use Disk Warrior and/or TechTool Pro to repair the hard drive. If neither can repair the drive, then you will have to erase the drive and reinstall from scratch.
3. Boot from your OS X Installer disc. After the installer loads select your language and click on the Continue button. When you reach the screen to select a destination drive click once on the destination drive then click on the Option button. Select the Archive and Install option. You have an option to preserve users and network preferences. Only select this option if you are sure you have no corrupted files in your user accounts. Otherwise leave this option unchecked. Click on the OK button and continue with the OS X Installation.
4. Upon completion of the Archive and Install you will have a Previous System Folder in the root directory. You should retain the PSF until you are sure you do not need to manually transfer any items from the PSF to your newly installed system.
5. After moving any items you want to keep from the PSF you should delete it. You can back it up if you prefer, but you must delete it from the hard drive.
6. You can now download a Combo Updater directly from Apple's download site to update your new system to the desired version as well as install any security or other updates. You can also do this using Software Update.