Mac doesn't start up from disc

Symptoms

If your Mac stops responding when starting up from a Mac OS X Install DVD, learn about some troubleshooting steps you can use. 

Products Affected

Mac OS X 10.4, Mac OS installation/setup (any version), Mac OS X 10.6, Mac OS X 10.5

Resolution

Try these troubleshooting tips one at a time until you are able to start from the disc:

1. Verify that the shiny side of the disc is clean (no particles or smudges on it). Here are some tips for cleaning a disc.
    
2. Make sure you are using the disc that came with the computer, or a newer disc that contains a compatible version of Mac OS X (look at version on the label of the DVD). Please see:
   • Don't install a version of Mac OS X earlier than what came with your Mac
   • Mac OS X versions (builds) included with Intel-based Macs
      
3. To verify that your Mac is attempting to start from the disc, hold the C key as your Mac starts up. You may hear access sounds from your computer's optical drive.
   • If holding C does not help, hold the Option key during startup. Startup Manager should appear. Select your Mac OS X disc icon, then press Return.
   • If Startup Manager does not appear, make sure you are using an external Apple keyboard (directly connected), or a portable Mac's built-in keyboard. Some third-party keyboards may not be recognized in time for Startup Manager to appear.
   • If you are able to start from your hard disk, you can use Startup Disk preferences in System Preferences to select the disc, then restart.
      
4. Temporarily disconnect USB and FireWire devices connected to your computer. If you are not using a portable Mac, connect your Apple keyboard and mouse directly to your Mac. If this resolves the issue, reconnect USB and FireWire devices one a time until the issue occurs again. Once a problematice device is located, contact the manufacturer for assistance.
    
5. Your Mac may benefit from a firmware update. The latest firmware updates are available from Apple Support Downloads.
    
6. If the issue persists, shut down your Mac, then remove third-party hardware upgrades such as third-party memory (RAM) and third-party expansion cards. If this resolves the issue, contact the manufacturer of the product for assistance.

Additional Information

In rare cases, a kernel panic message may appear when you can't start from a Mac OS X disc.

Note: If you're having difficulty starting up from your hard drive, see Gray screen appears during startup instead.