Dealing with Startup Problems in Your Mac
What if you can't even get the computer to start? (That is a very unusual circumstance.) You probably have no power because the plug came loose (blame it on the dog or cat), the switch on the power strip is off, your battery ran out of juice, or a blackout has occurred in your neighborhood.
On some laptops, you can tell whether a battery needs recharging by pressing a small button on the battery. Lights on the battery let you know how much strength the battery has left.
Here's another thing to try: Press the Power button; hold down the Command, Option, P, and R keys; and wait until you hear the startup chime a second time.
If you've added memory, installed an AirPort card, or installed another component and the machine fails to start, make sure that these items are installed properly and try again. If your computer still can't be revived, try removing the memory or card you just installed and give it another shot.
After that, if you still can't restart, you may have to seek warranty service. Another option is to reinstall the operating system.
Reinstalling OS X
If a problem has truly brought your computer to its knees, it may be time to reinstall your favorite operating system. It's bad enough that you have to suffer through the hassle. Moreover, you're understandably panicked about retaining files and user settings.
Follow these steps to reinstall OS X:
1. Insert the OS X installation disc in your CD or DVD drive.
2. Double-click the Install Mac OS X icon, and go through the usual installation drill.
3. When asked, choose your current OS X disk as your destination disk (which in all likelihood is your only option anyway).
4. Click Options.
You've arrived at an important point in the process.
5. To salvage existing files and settings, select Archive and Install and then Preserve Users and Networks Settings. If you prefer starting anew, select Erase and Install, keeping in mind that you can't undo it.
6. Click Continue.
7. To install certain parts of OS X, click Customize. To perform Apple's recommended basic installation, click Install.
8. Because the OS X disc you have may not have all the latest tweaks, pay a visit to Software Update (found on the Mac menu) to bring Tiger up to date.
A retail version of OS X may differ some from the version that was loaded on your computer.
Reinstalling OS 9
Reinstalling OS 9 or, for that matter, running so-called classic apps is no longer an option under Intel Macs. But if you have an older machine, you can install a Mac OS 9 System folder with an OS 9 install CD or OS X installation discs. In the former, hold down the C key as your Mac restarts. This lets you start from the disc in your optical drive. If using an OS X disc, insert the Additional Software & Hardware Test disc. Then double-click Install Additional Software, and you'll be guided on-screen from there.