1. Place the Mac OS X Install DVD into your computer and select 'Restart' from the Apple menu. Hold down the 'C' key on the keyboard when you hear the chime.
2. Click 'Continue' until you get to the menu screen. Select 'Utilities' or 'Disk Utility' from the menu.

3. Select your Mac's hard drive and start-up disk. Hold down the 'Command' key to select more than one disk.
4. Click 'Repair Disk.'