Command-arrow interrupt not handled by latest build (11G63?) of 10.7.5.

Question

System fails to respond to the Command-left-arrow and Command-right-arrow shortcuts in any app for which they used to work (specifically iCal and Word). This behavior began after I did the system update on March 20.

Answer 1

Back up all data.
Boot in safe mode.* This will cause certain caches maintained by the system to be rebuilt. The instructions provided by Apple are as follows:
Shut down your computer, wait 30 seconds, and then hold down the shift key while pressing the power button.
When you see the gray Apple logo, release the shift key.
Safe mode is much slower to boot than normal.
When the login screen appears, reboot as usual (not in safe mode) and test. There's no need to log in while in safe mode.
*Note: If FileVault is enabled under OS X 10.7 or later, or if a firmware password is set, or if the boot volume is a software RAID, you can’t boot in safe mode. In that case, proceed as below.
You must be logged in as an administrator to carry out these instructions.
Triple-click the line below to select it:
sudo update_dyld_shared_cache -force
Copy the selected text to the Clipboard (command-C).
Launch the Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.
Paste (command-V) into the Terminal window. You'll be prompted for your login password, which won't be displayed when you type it. You may get a one-time warning not to screw up. If you see a message that your username "is not in the sudoers file," then you're not logged in as an administrator.
Reboot and test.