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Troubleshooting your Mac

Troubleshooting your Mac involves two basic tasks: figuring out what the problem is, and fixing it. Usually the figuring out is a LOT more difficult than the fixing. Here we're going to outline a simple procedure for diagnosing Mac problems. The main thing to keep in mind is that the Mac works in a logical way. We take a very scientific step-by-step approach to solving problems on a Mac. If you are systematic, you will be able to fix virtually any problem short of a faulty electrical component (a very rare occurrence in most Macs).

Identify the symptoms

We usually break this down into four categories.

  1. No power
  2. Mac won't start up: blinking question mark ?   or crashes during startup process
  3. Frequent random crashes from many programs and/or the Finder
  4. Bad behavior from one program

There are lots of other, more subtle problems, or problems related to a specific piece of hardware or software, but these four are the major ones that most Mac users might face.

Identify possible causes

Problems almost never appear on a working Mac all by themselves. Unless your machine is brand new, your problem was probably caused by some change that you have made to your computer.

  1. Have you added any new software recently or changed anything significant in your Mac's System Extensions or Control Panels?
  2. Any changes to your hardware new RAM or a new SCSI device?
    These can cause a variety of problems from failure to boot, frequent crashes, or just failure to properly copy data.
  3. What where you doing just before the problem first occurred?
    Re-creating the problem can help to identify it.

Putting it all together

OK, given the information above, you should be able to figure out what is wrong and fix it. Keep in mind that only very rarely does a working Mac develop a problem that requires a visit to an authorized technician. Usually you can either fix it yourself, or get an expert to help you fix it by phone, e-mail, or on the Web.

Power problem

This is a hardware problem. Either you can fix it in 5 minutes or your Mac will need service.

But first go through these diagnostic steps:

  • Check if there is truly no power to the computer, or if the monitor is just not turning on test this by checking if the little green light is on for the computer and for the monitor. Some monitors show an amber light when there is no input from the computer.
  • Check if the Mac and monitor are plugged in.
  • Check if there if the power is working in that outlet. (test with a lamp)
  • Check the cables to see if the monitor is properly connected to the Mac maybe you have moved the Mac or the monitor recently

If everything is plugged in and the outlet is OK, but the computer's little green light is not on, then you have a problem with the computer's power supply. If you are confident about your technical skills unplug the computer and open up the case to find the power supply (a big metal box) and jiggle it around a bit to try to set it more firmly into place.


Stu has a machine that gets moved around a lot and occasionally needs a hard bang on the power supply to get it properly connected.

If this doesn't solve your problem, then you are probably going to need a new power supply take the Mac to the nearest Authorized Dealer.

Startup problems

  1. Crashing during startup

This is a classic case of an Extensions conflict. Try restarting with all Extensions off by holding down Shift key during restart. If this solves the problem then visit our Extensions conflict clinic to take you through the complete procedure for solving this problem.

If restarting with Extensions off doesn't solve the problem, then you are going to need to do a Clean System Install visit our Clean Install clinic, we'll walk you through the complete procedure .

  1. The blinking question mark   ?
Startup Disk Control Panel

This is your Mac's way of saying that it cannot find a valid System Folder. If it only blinks for half a minute and then starts up normally, then this can be fixed by going to the Startup Disk Control Panel and selecting your hard drive.

Most often, this problem is caused by a corrupted disk driver on your hard disk. This can be caused by installing a System Update or messing around with disk formatting utilities (including drivers for external drives such as Zip drives, Syquests, etc.). Sometimes a disk driver gets messed up for no apparent reason.

Sometimes you can fix a corrupted disk driver with the Apple HD SC Setup program its comes with the Apple sytem installer (check your CD). To use this, you will first need to boot your Mac with something other than the system on your hard drive. Any of the following will work: a System CD-ROM, a Disk Tools floppy disk, an external hard drive, a Zip disk with a functional System installed on it (my favorite Mac fix-it tool).

If your Mac stubbornly refuses to recognize an external system, then you will need to force it to ignore the System on the internal hard drive this will take some keyboard gymnastics during the startup process. The key combination is: [Command + Option + Shift + Delete] while also hitting the Power button on your computer! This requires at least 3 hands! It can be done by holding the [Command + Option + Shift] keys with one hand, hitting the Power button with the other, then quickly hitting the Delete key when the startup chime sounds (or take your shoes off and get some toes free for those extra buttons).

Once you have the machine booted up from an external system, launch Apple HD SC Setup and hit the "Update" button. Then try to restart your machine. If this does solve the problem, you will probably need to reformat the hard drive. This means completely erasing all data (all files and all applications) on the drive. It may be possible to rescue everything off the hard drive by first booting from an external system like we just described. You can then use Apple HD SC Setup (or a third party disk driver such as the FWB Hard Disk ToolKit) to reformat your hard drive. Visit our Reformat HD clinic for details.

Frequent random crashes from many programs and/or the Finder

This is a classic sign of a bad System Folder with the slight possibility of being an Extensions conflict or SCSI problem.

You can narrow it down with this procedure:
Disconnect all SCSI devices and Restart with Extensions off by holding the Shift key down. If the problem persists, you have a corrupt System. Rather than messing around with all of the complexities inside your System Folder looking for the ultimate source of the problem, just perform a clean System Install. Visit our Clean Install clinic for a step-by-step guide.

If disconnecting the SCSI cables fixed the problem, then check out our guide to SCSI Voodoo.

If turning off all Extensions corrected the problem, then you should check out our Extensions Conflict clinic.

Bad behavior from one program

This is almost always due to problems with Preferences. Just delete the Preferences file for that program from the Preferences folder in the System folder. Beware, certain programs store serial numbers and other key information in their preferences files be sure that you have these numbers on hand or copy them down from the program before you delete the Preferences files.

System folder--Preferences folder

If this does not solve the problem, then you may have a corrupted program or an Extensions Conflict. Trash the offending program and all of its associated Preferences and Extensions, then reinstall the program from your master disks. If you still have a problem, look for an Extensions conflict between Extensions installed by this program and something else on your System. Check out our Extensions Conflict clinic for help on solving this problem.

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