When you press that start key and nothing happens, it's more than an inconvenience.

If you're like a lot of Mac users, it's a betrayal. Suddenly, this faithful friend and servant that has worked with you for so long has decided to "check out" on you.

Remember, however, that Apple has traditionally taken very good care of its treasured customers. If your machine is still under warranty, they'll even send someone to your domicile to correct the problem. But even if its out of warranty, the Apple has been designed to be extremely user-friendly - and there are very few problems that the user can't often solve on his/her own.

The folks at Creative Techs have come up with a  handy four-step process to get you back up and running:

1) Start In Safe Mode

This is based on the fact that many Mac problems are due to extension conflicts. Your Mac worked when you brought it home, but since then, you've probably installed a lot of third-party applications. The logical answer is to restore you Mac to its original condition:

a) Hold down the "Shift" Key while turning on the Mac
b) Release "Shift" when a gray Apple with a spinning gear appears
c) The words "Safe Boot" should appear during startup or in the login window.

Starting in Safe Mode takes a bit longer, especially for larger hard drives.

2) Single-User Mode

a) Hold down the Command as "S" keys while starting up. A black screen with white text appears.
b) When prompted, type "fsck -fy" (without quotes)
c) Press "Return. If you get a "File System was Modified," keep repeating Step 2 until you get "No problems were found."
d) Type "reboot" (without quotes) and hit "Return."

NOTE: A utility called "Applejack" can simplify this process.

3) Boot Up From Apple CD/DVD

This is a classic (and a Classic) fix from Apple's earliest days, and always worked for me.

a) Insert the Mac OS X Install disc.
b) Hold down the "C" key while turning on your Mac. Release when you see the gray Apple.
c) For Mac OS  10.2.x - 10.3.x, choose Installer>Open Disk Utility.  In Mac OS  10.4.x, choose Utilities>Disk Utility.
d) Select your HD icon on the left and click "Repair Disk" in the First Aid tab.
e) When no errors are reported, click "Repair Disk Permissions."
f) Reboot your Mac as usual.

4) If the three techniques above don't work and you have another Mac or a MacBook lying around, you can use it to start up the troubled Mac:

a) Hold down the "T" key while starting up the troubled Mac. Release this key when the FireWire icon appears (see right).
b) Connect the troubled Mac to your MacBook (or other desktop model) with a FireWire cable.
c) Open the Disk Utility on the functioning Mac (in Applications/Utilities)
d) Select the problem Mac's icon on the left, then click "Repair Disk" in the First Aid tab.

If nothing else, you will be able to recover important data from the sick Mac using this method.

If these steps fail, chances are the problem is serious and will require the attention of a professional. However, chances are very good - about 99 out of 100 - that whatever ails your Mac can be addressed using one of the above procedures.