Am I correct in saying leaving the disk in just makes the install process, or live CD start again? If so, you can set your bios to boot from hard drive 1st, then cd. Make sure to change back if you want to boot from cd later.
Also, depending on your computer, you may be able to select the boot device under boot options when it 1st starts.
This being said, if neither of those work, see the previous post about the pin hole in the front of the cd to eject after powering down the machine. Use a paper clip. Let us know if this helps. Thanks