From apple:
If a disc in your computer's optical drive refuses to leave, try these steps to eject the disc.
Restart your computer: From the Apple menu, choose Restart.
When you hear the startup sound, immediately hold down your mouse button until your computer starts up and ejects the disc.
If that doesn't work, try this:
Restart your computer: From the Apple menu, choose Restart.
When you hear the startup sound, immediately hold down the X key until your computer starts up.
Open iTunes or DVD Player (both are in the Applications folder).
Click the Eject button in either of these applications.
If that still didn't eject the disc, try this:
Restart your computer: From the Apple menu, choose Restart.
When you hear the startup sound, immediately hold down the Command, Option, O, and F keys together until you see a text-only screenthis is the Open Firmware screen.
At the prompt, type eject cd and press Return.
Then type mac-boot and press Return to start up your computer in Mac OS X.
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