A.6. Erase Install

A.5. The Clean Install

In Mac OS 9 and Windows, the clean install is considered an essential troubleshooting technique. It entails installing a second System Folder or Windows folder ”a fresh one, uncontaminated by the detritus left behind by you and your software programs.

In general, though, you and your software can't invade the Mac OS X System folder. The kind of gradual corruption that could occur in those older operating systems is theoretically impossible in Mac OS X, and therefore the need to perform a clean install is almost completely eliminated.

That's the theory, anyway. In fact, somehow or other, things do go wrong with your Mac OS X installation. Maybe you or somebody else has been fiddling around in Terminal and wound up deleting or changing some important underlying files. Certain shareware programs can perform deep-seated changes like this, too.

The point is that eventually, you may wish you could just start over with a new, perfect copy of Mac OS X. And now, thanks to the clean install ("Archive and Install") option, you can ”without having to erase the hard drive first.

Start by following the preceding steps 1 through 3. On the Select Destination screen, though, click Options. Now you're offered four kinds of installation. Turn on "Archive and Install." ("Preserve Users and Network Settings" should be on, too.)

This powerful option leaves all of your accounts (Home folders, documents, pictures, movies, Favorites, email, and so on) untouched . As the option's name implies, it also leaves your network and Internet settings alone. But it deactivates your old System folder (you'll find it, later, in a new folder called Previous System Folders) and puts a new one in its place. And that's exactly what you want.

Click OK and then continue with the previous step 4. When it's all over, you'll be confident that your Mac OS X installation is clean, fresh, and ready for action.