Manage a hanging 'Print & Fax' system preferences in OS X
Printers in OS X are generally managed through the Print & Fax system preferences, but some problems might result in these preferences hanging. Here is how to clear this if it occurs.
Printers in OS X are generally managed through the "Print & Fax" system preferences, and when there are problems with your printer setup one of the ways you can quickly revert back to default settings is to reset the print system. This can be done by right-clicking in the printer list and choosing the "Reset printing system..." option that should be available in the contextual menu.
Unfortunately, some problems with the printing system may result in the Print & Fax preferences hanging or crashing when opened, resulting in the inability to use the system's reset option.
The first step to try when initially troubleshooting problems with printer settings is to check the System Preferences from an alternative administrator user account (create a new temporary one if needed--it can always be removed at a later date). This will help you see if the issue is with an account-specific setting or if the problem is more global in nature. If the problem does not appear in the new admin account, then it is likely a corrupt setting or cache in the initial user account that may be responsible for the problem.
The System Preferences tool is just an application like any other in OS X that has its own preferences file and other temporary files for each user account that interacts with it. As with other applications on the system, removing the preferences file to force its recreation is one approach to fixing problems such as crashes or hangs. The preferences file for the System Preferences is called "com.apple.systempreferences.plist" and is located in the /username/Library/Preferences/ folder. In addition you might try running afrom the affected account, specifically focusing on removing user caches.
If the problem does persist in alternative accounts, then the next step is to look in more depth at the behavior of the print system by invoking print functions in various programs and by checking any output warnings or errors in the Console utility. If printing in various applications results in a hang or crash of that application, then it is likely there is a problem with the core printing system that is resulting in hangs whenever the print system is accessed, either by applications or by the System Preferences.
You can further check the Console utility to see if there are any listings that include the words "cups," "cupsd," or "org.cups.cupsd." If the print system is crashing or failing to start properly, you will likely see the messages describing the process "launchd" attempting to respawn the cups process after a set amount of time (usually 10 seconds).
To reset the print system if crashes or hangs are preventing you from accessing the Print & Fax system preferences, the first step is to fully shut down the printing system to prevent it from causing the crash. To do this you will need to interact with the system launcher (launchd) through the Terminal application. Open the Terminal and enter the following command (copy and paste it all on one line):
sudo launchctl unload /System/Library/LaunchDaemons/org.cups.cupsd.plist
The file "org.cups.cupsd.plist" contains a set of parameters that the system launcher (launchd) loads at startup and uses to run and manage the "cupsd" background printing process. This command uses the "launchd controller" (launchctl) to tell the launcher to unload these settings and thereby prevent the launcher from attempting to start up the printing process.
When the printing system has been disabled, open the System Preferences and go to the "Print & Fax" pane, which should now load without hanging. Since the printing system is shut down you likely will not see any printers listed in the preferences pane, but that is OK since you now can use the pane to reset the printing system. Right-click on the empty printer list and choose the option to reset the printing system, and the print system should now be at its default settings.
After the print system is reset, restart the computer to have the launcher automatically reload the cups property list file (or you can rerun the Terminal command above using "load" instead of "unload" in the command), and then return to the System Preferences and set up your printers again.