OS X is a robust operating system; while problems are rare, they do show up from time to time. Since these issues always
seem to present themselves at the worst possible moment, it helps if you know the best ways to troubleshoot them. That’s
what this chapter is all about, and it’s a great reason to keep this book in your pocket!

Common Problems
There are a lot of things that can go wrong with your Mac: Hardware problems, software glitches, and configuration issues
can happen at any moment. Most of the problems you’ll encounter can be easily addressed or diagnosed by following
these steps

However, some issues are unusual or won’t respond to the fixes listed in this chapter. A great resource for those situations is
Apple’s website: www.apple.com/support. As you’d expect, you can browse manuals and tutorials on that site. More useful
when trying to fix that quirky problem, though, are the communities you can access via that site, where you’ll likely find
someone who’s having the same problem you are—and the fix.
If the information there doesn’t resolve things, you could have a unique issue, in which case a trip to your local Apple Store or a call to Apple is in order. You can find a complete list of technical support numbers for Apple at www.apple.com/support/
contact/phone_contacts.html. In the United States, the number is 1-800-275-2273.

Misbehaving Applications
One of the most common problems on a Mac is an application that isn’t behaving as expected. This issue comes in many
forms: an application that unexpectedly quits repeatedly, stops responding, or just doesn’t perform the way it normally does.
This section suggests ways to resolve all these issues and more.

An application stops responding

Occasionally, an application will simply stop reacting to anything. Your mouse or trackpad will still work, and other programs
will be fine, but if you want to use the troublesome program, all you’ll get is a spinning beach-ball cursor (instead of
the mouse pointer) and you’ll have no way to input anything. Don’t panic—there’s an easy fix. Simply right-click or Controlclick
the stalled application’s icon in the Dock to bring up its Dock menu (Figure 4-1). If you see Application Not Responding
in faint text at the top of the menu, you’ll also see a Force Quit option. Select Force Quit and OS X will kill the program.
You may also need another way to kill applications, because occasionally a program can become unresponsive without
OS X realizing that the program is in peril. For these times, launch the Force Quit Applications dialog box either by selecting
→Force Quit or using the key combo Option-⌘-Esc. You can also try holding down Shift as you click the menu,
then select “Force Quit [application name]” to kill the front most application.
There’s some good news when it comes to force quitting applications in Mountain Lion. In the old days of OS X (before
Lion), any changes you made between the last time you saved a document and the moment the application started misbehaving were gone forever. But thanks to Auto Save, if you’re forced to quit an application, Mountain Lion preserves the work you’ve done since the last time you manually saved.

WARNING
“Save early, save often” is still good advice, since Auto Save works only with applications specifically built with Auto Save in mind. That means that work you do in apps designed for Lion or Mountain Lion will be saved, but applications that haven’t been updated since Lion came out won’t automatically save your work. 

The Finder stops responding
The Finder is just another program, so it can get hung up, too. If that happens, either head to →Force Quit or use the key
combination ⌘-Option-Esc. If nothing happens, try clicking the Dock or some other application first, and then use the
menu or ⌘-Option-Esc to invoke the Force Quit dialog box.

NOTE
When you select an application in the Force Quit dialog box, the dialog box’s button reads “Force Quit.” However,
if you select the Finder, the button reads “Relaunch” instead. Why? Unlike every other application, the Finder will be restarted immediately after it’s forced to quit.

Force quitting greedy processes
If you suspect something is eating up too much processor time or hogging too many system resources (because your Mac is
running really slowly, say, or the fans are running at full speed for no obvious reason), Force Quit won’t help you figure out
which application is the culprit. Instead, open Activity Monitor (Applications→Utilities→Activity Monitor), click its CPU tab
in the lower half of the window, and then look for any processes that are using a lot of CPU resources for more than a few seconds. (Safari and its helper applications occasionally do this, particularly with runaway Flash or JavaScript code.) When you
identify a suspect, single-click the renegade process’s name and then click the big red Quit Process button (you can’t miss it—
it’s shaped like a stop sign).

WARNING
Be careful which applications you quit in this way. There are some programs that your Mac runs in the background,
and many of these are important in helping your computer operate normally. Here’s a rule of thumb: if you don’t recognize the name of the program as an application that you launched, don’t kill it. Instead, do a Google search on its name (for good measure, include the terms “OS X” and “cpu,” too). Chances are good you’ll find a solution for whatever is causing that process
to use up so much CPU time.

USB device problems
It seems like computers never have enough USB ports, so most of us end up using USB hubs (or keyboards that have extra USB
ports). Then we plug some fantastic new USB device into the hub—and it doesn’t work. In fact, if you dig through System
Information (it’s in the /Applications/Utilities folder) and look at the USB Device Tree (click USB in the list on the left), the
hub shows up, but not the device.
Often the problem is that the device requires a powered USB port and you’re using an unpowered hub (or you’ve maxed out
the power capabilities of the hub or port). Switching to a powered hub might fix the problem, but that isn’t guaranteed.
What works most often is plugging the device directly into your Mac, which means you’ll need to shuffle your various USB devices
around. If any of them can run off of their own external power supply rather than taking power from the USB port, that
may help as well (sometimes these power supplies are sold separately; check with the device’s manufacturer).
The second method of attacking USB device problems is a little more involved. First, shut down your Mac and unplug all the
USB devices (even the ones that use external power supplies).

Reboot your Mac, and then plug them back in one at a time while watching the USB Device Tree (it’s updated quickly so
you’ll see each device appear as it’s plugged in) to figure out which device isn’t playing nicely with others. Sometimes going
through this process results in all the devices suddenly working. But if you discover that only a certain device isn’t working,
the fix may be to install a new driver for it. Check the manufacturer’s website for updates.

Battery problems
MacBook users are faced with a problem that desktop users don’t have to worry about: the battery. The goal of most Apple
batteries is to still provide 80% of the original charge capacity after a certain number of cycles (charges and discharges). The
number of cycles varies depending on your machine. For Mountain Lion–capable MacBooks, the cycle count is either
750 or 1,000 cycles (depending on the model). If you notice
your battery isn’t holding a charge for as long as it used to, the first thing to do is launch System Information (Applications→
Utilities→System Information) and then click Power in the list on the left; The Battery Information list includes your battery’s full charge capacity, how many cycles it’s been through, and its condition. If the condition is listed as Replace Soon or something equally ominous, it’s time to think about getting a new battery. If the cycle count is low but the battery is still running out of juice
prematurely, here are a couple of things you can try:

Calibrate the battery
Inside every MacBook battery is a microcontroller that tells your computer how long the battery is going to last until it runs out of juice. Over time, this estimation can get further and further from real-world performance. To get the computer and the microcontroller on the same page, you need to recalibrate the battery from time to time. To do so, fully charge the battery and then keep your computer plugged into the power adapter for two more hours. Next, unplug the power adapter and fully drain the
battery. When a warning pops up alerting you that the battery is running dangerously low, save your work and keep on trucking until your computer automatically goes to sleep. Then let the computer sleep for more than five hours to make sure every drop of power is gone. Finally, plug in the power adapter and let your computer fully charge. The battery indicator should now be successfully recalibrated.

NOTE
If your MacBook has an internal battery, Apple recommends not calibrating the battery because these internal batteries should be serviced only by an authorized repair center.

Reset the SMC
SMC is short for the System Management Controller, a chip that’s responsible for hard drive spin-down, sleeping your Mac, waking your Mac, and keyboard backlighting. A malfunctioning SMC can prevent the battery from charging, so you need to reset the SMC. How you do that depends on whether your MacBook has an internal battery (like all the newer MacBooks) or a battery that you can easily remove. If it has a removable battery, shut it down, unplug the power adapter from the wall and the computer, and then remove the battery. Next, press the power button for five seconds. After that, replace the battery, plug in the power adapter, and then restart the computer. If your MacBook has an internal battery, shut down the computer and plug it into an adapter that’s getting power. On the left side of the keyboard, hold down Left Shift-Control-Option, and then press the power button. 
Keep all these buttons depressed (including the power button) for five seconds and then release them all simultaneously.
Pat yourself on the back for pulling off an impressive feat of manual dexterity, and then press the
power button to restart the computer.
If those remedies don’t restore your battery, it’s likely time for a trip to the local Apple Store or authorized repair center. If
your computer is under warranty and your cycle count is low, Apple will probably replace the battery for free. If your cycle
count is over the recommended number and the performance degradation is within expectations, you’ll probably need to pay
for a new battery or live with the reduced (and ever-shrinking) battery capacity.

NOTE
Like many computer makers, Apple has had its share of battery recalls, both for safety and performance reasons. So check with Apple to see if your battery is under recall. If so, it’s likely that it will replace the battery even if your computer is out of warranty.

Display problems
Most Macs come with a built-in display that doesn’t require special configuration, so display problems are uncommon.
When they do happen, they’re often caused by user error. The fix, while usually easy, isn’t readily apparent. Here are some
things to try: 

Fuzzy/tiny display
If your display is fuzzy or everything is suddenly bigger than you remember, it’s possible that someone changed the display’s resolution (on some systems, this may also manifest itself as a small screen with black bars around its edges). Head to →System Preferences→Displays and look for the monitor’s native resolution (on Macs with built-in displays, this is usually the highest resolution available—the one at the top of the list). Once you select the optimal resolution, things should look normal again.

Your display moves with your mouse The weird thing is that this always happens when children under five are on your lap while you’re using your computer. Is there some kind of kid detector in your Mac that causes this? Nope—your kid just pressed some keys while you were working. (If you don’t have kids or lap cats, then it was probably you.)
There are a couple of key combinations that will cause your Mac to zoom the screen. The most common is holding down Control while you zoom in or out with your mouse or trackpad. Once you’re zoomed in, your mouse will suddenly start dragging the screen around, which is disconcerting if you aren’t expecting it. To turn it off, hold down Control and zoom out with your trackpad or mouse wheel.
There are a couple of other key sequences that can be invoked accidentally: Option-⌘-8 toggles keyboard zooming on and off, and holding down = or − while pressing Option-⌘ zooms in or out, respectively.

Startup Problems
A misbehaving application is bad enough, but a Mac that won’t start properly is truly disconcerting. The good news is that
most such problems are repairable. The general method of attack in this case is to get your Mac to a state where you can run
Disk Utility and repair the drive. However, there are some situations where you can’t even get to that point.
Your Mac beeps instead of starting If your Mac just beeps at you when you try to start it up, it’s trying to tell you something: one beep means there’s no memory (RAM) installed, and three beeps means your RAM doesn’t pass the integrity check. The problem could be a bad RAM module, so you’ll need to open up your Mac and replace the module.

Try installing some memory that you’re certain is fully functional to see if that resolves the problem. If you don’t have any spare memory lying around, try removing all the RAM modules and then replacing them one by one until you’ve isolated the bad module.

NOTE
If you don’t know how to replace memory in your Mac, check the user guide that came with it. Or if your Mac is still under warranty, just take it into an Apple Store for service.
Your hard drive is making noises If you suspect you’ve got a physical hard drive problem, you need to check things out quickly before they get much, much worse. If you hear a strange noise coming from your machine, that’s an obvious sign of a hard drive problem, but these issues can also be indicated by the computer stalling for several seconds at a time (or making a clicking sound when stalling).
Just as with a car, when a bad sound is emanating from your hard drive, it’s usually a bad thing. If you’ve ever listened to National Public Radio’s Car Talk, you know that one of the highlights is when callers try to imitate the sounds their cars are making. If you’re inclined to try identifying your hard drive’s sound by ear, head over to http://datacent.com/hard _drive_sounds.php and take a listen to the sounds of dying drives, sorted by manufacturer.

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