Is there a preference plist for playing DVD or CD that might be corrupt?

Usually when an optical drive immediately eject a disc it means the optical drive has failed.

If this is an external USB optical drive, then try using a dual plug USB cable so that you plug in two USB connectors to the computer to supply more power to the optical drive just in case the drive isn't getting enough power.

Does it make any attempt to read the CD? You can usually hear the laser assembly moving back & forth trying to read the CD. If it is making attempts to read the CD, then maybe the laser/lens assembly is dirty (use a CD cleaning disc to attempt to clean it), or the CD may be defective (CDs can degrade over time) or scratched/dirty.

Is the CD one which someone burned (aka created) or is it a retail/factory made disc?

Have you tried a DVD in the drive? Sometimes when the laser assembly begins to fail the laser will become too weak to be used for reading discs. Sometimes a DVD can be read when a CD cannot (or vice versa). If this is the case the optical drive is failing.