Back in the day of Mac OS 7.x-9.x, if you had a problem, one of the first thing you would think of is extensions conflicts. To test this theory, you would boot up holding the shift key to disable extensions. Well, Apple has added the same thing to Mac OS X. If you hold down the shift key at startup, you will do a Safe Boot into Safe Mode. In this mode, you startup disk is automatically checked for errors, only the required kernel extensions are loaded, and only Apple-installed startup items are loaded. This way, you can see if that newly installed software is conflicting with some system level software.

Like all other OS's, corrupted hard drives can give you a lot of trouble. Making sure your drive is in tip top condition prevents 90% of all problems you can have with computers. Luckily, Unix has a nice command to help you repair your disks. To use it, you will have to start up in Single User Mode (by holding down Command+S during startup), until you get a text prompt. Here, you type in "/sbin/fsck -y" repeatedly until you get a message saying "The volume appears to be OK." Once that happens, type reboot to restart your Mac. Alternatively, you could start up using the Mac OS X CD, and using the Installer to run the Open Disk Utility from the Installer menu.

There are now a couple third party disk utilities that are compatible with OS X. Micromat's TechTool Pro 4, Norton Utilities, Norton Systemworks, and Alsoft Disk Warrior are all able to handle Mac OS X files. When fsck isn't enough, use one of these utilities. HINT: Keep in mind that as of this writing, only TechTool Pro 4 can repair a disk from a CD booted into Mac OS X. The other utilities boot in OS 9, and thus will not work on some of the newer machines.

Mac OS X does have some quirks sometimes such as graphical artifacts, things not showing up, or changes not being applied. If you have made sure you did everything right, log out and log back in via the Apple menu. This is nearly identical to restarting, except it is MUCH faster. Then, retry what you were having problems with, to see if it works now.

Remember how force quitting applications in the classic Mac OS would usually not work, and 9 times out of 10 bring the entire system down? That has all changed with OS X. Because of Unix's protected memory, using command+option+escape now brings up a window, with a list of applications to force quit (including the finder). Once you do a force quit, you are free to work on anything you wish, including launching that application again, and starting over with it. No longer is Force Quitting a lesson in futility.

Because of Mac OS X's Unix structure, it's not uncommon to run into problems with permissions. These problems can be very odd in nature, and hard to actually troubleshoot. By using the Disk Utility in your utilities folder, you can repair the permissions of your startup disk.

Mac OS X has some built in maintenance tasks that are scheduled to run very late at night. If you shut down or sleep your computer at night, these tasks will not get run. To run them at your leisure, you can use a utility such as MacJanitor.

Mac OS X makes extensive use of cache files to hold all different sorts of information. Sometimes, these caches can become corrupt, making their associated programs unstable. To easily clean out your computer's caches, use a utility such as Jaguar Cache Cleaner.

Just like in the Mac OS of old, preference files can become corrupt. This can cause a program to stop running correctly, or just acting strange. One of the first things you should do if this happens is delete the preference file(s) associated with that program. To assist in finding corrupt preferences, use the program Preferential Treatment.

New to the Mac OS X 10.2 installation process is an Archive and Install option. This option allows you to easily backup users settings, and installs a fresh copy of OS X. If you get to the point where a reinstallation is necessary, try this option first. If you need instuctions on how to do this, see this Knowledgebase document.

Various system settings are stored in this RAM, and they can become corrupted from time to time. If you are experiencing strange problems, try resetting the PRAM by holding down the command+option+P+R keys while starting up. Keep holding down the keys until your hear the startup chime two times. Let go of the keys, and the computer will continue to start up.

Another type of RAM that stores obscure settings (most notably firmware), is the NVRAM. Again, if this becomes corrupted, very odd problems could crop up with your Mac. To reset the NVRAM, holding down the command+option+O+F keys while starting up. This will start you up into Open Firmware, where you can enter commands into the prompt. Enter the folling commanrds to reset the NVRAM and restart your Mac:

1. reset-nvram (hit return)
2. reset-all (hit return)

The Power Management Unit controls various I/O aspects of Apple laptops. If the PMU is corrupt, a wide variety of problems can occur. To reset the PMU, follow the directions on the Apple Knowledge Base.

Similar to the PMU for laptops, desktops Macs have a microcontroller that handles many I/O functions. Again, if this becomes corrupt, strange happenings can occur. To reset the CUDA switch, you will have to open your Mac, and look around on the motherboard for a white button (many times it is near the RAM slots). Press this button once (only once) to reset the CUDA.

AppleJack is a command line utility to be run in Single User mode. It allows you to repair permissions, fix disk errors, check preference files, and clear cache files all without launching a GUI (Graphical User Interface).

If your /tmp file is suddenly missing, various action such as starting Classic, printing, software update, file sharing, and burnings discs will not function. To fix this, open up the Terminal and type:
sudo ln -s /private/tmp /tmp
Hit return, enter your admin password, and hit return again. Those services should now be available.

• Shift=Safe Mode
• Command + S=Single User Mode
• Command + V=Verbose Mode (watch the Start-up status)
• Option=Volume List (A.K.A Startup Disk)
• Command + Option + P + R=Reset PRAM
• Command + Option + O + F=Start into Open Firmware

• MacFixIt
• Micromat (Makers of TechTool Pro 4)
• Symantec (Makers of Norton SystemWorks)
• Alsoft (Makers of Disk Warrior)
• MacJanitor
• Jaguar Cache Cleaner