A number of users flooded Apple Support Communities forums following yesterday’s release of the Mac OS X Lion 10.7.3 update to complain about dreaded CUI errors. In addition to a bunch of minor issues, some people reported being greeted with unexpected app crashes after rebooting into 10.7.3. For them, attempting to launch any application would produce the above  (and below) prompt saying:

The application unexpectedly quit after trying to restore its windows. Do you want to try to restore its windows again?

Log files reveal that the affected users are often unable to use their computer normally as a large number of crashes are being logged. Luckily, there are several easy workarounds to fix this annoying bug…

A forum user who goes by the nickname “nmphotog” has a simple solution: Don’t install the update through the operating system’s Software Update mechanism, which only retrieves 10.7.3 update files specific to a user’s current OS version. Instead, download the combo installer from Apple’s website that weighs 1.2GB, run the installer, restart into 10.7.3 and use Disk Utility afterwards to check for broken permissions and other disk-related issues. If you cannot apply the combo installer on the affected system at all, try booting into Safe Mode by holding down the Shift key during startup until the desktop or login window appears.

If this does not work, you will need to use another Mac. Simply boot the affected system in Target Disk Mode by holding down the “T” key during startup. Plug the computer into another Mac using a Thunderbolt or FireWire cable and run the combo installer on another Mac against the affected machine’s boot drive.

For some, their Mac is so adversely affected that none of this works— not even Target Disk Mode. Hopefully, they would have a Time Machine backup created before applying the 10.7.3 update. If that is your story, restore your computer from the most recent Time Machine backup, apply the combo installer and you should be fine.

If all fails, the last resort involves booting into a Lion Recovery partition on a boot volume or USB stick:

– Boot into the Recovery partition by holding down the Option key at startup. – Choose “Disk Utility” from the Menu bar and mount the combo installer image file
. – Choose “Terminal” from the Menu bar and run “installer -pkg /Volumes/Mac\ OS\ X\ 10.7.3\ Update\ Combo/MacOSXUpdCombo10.7.3.pkg -target /Volumes/Macintosh\ HD” (Change the target to reflect the startup volume’s name.) Be patient, as it can take up to 15 minutes or more to apply the combo update. – Run “reboot” and you are done.

If you do not have the combo installer at hand, follow these steps after booting into the Recovery partition and before executing Terminal commands:

– Select “Browse for help online” to launch the Safari browser
. – Visit http://support.apple.com/downloads/ and download the 10.7.3 combo update [direct link]. 
- Quit Safari after the combo installer is successfully downloaded. – Open Disk Utility from the Menu bar, choose “Open Disk Image” from the File menu and select the combo installer from where you saved it. – Quit Disk Utility after the volume is mounted and apply the aforementioned Terminal commands.

You may also want to check out additional tips and resources provided by OSXDaily. Let us know in the comments if these tips work for you and remember to always backup your system before any major OS update.

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