I have a 1.42 Ghz G4 Mac Mini 2005 original model. It has a combo optical drive. Whenever I insert a DVD or a CD the optical drive makes a clicking or you can call that a screeching noise. Let's say I am playing a movie DVD, when the disc starts playing it makes that noise, also when I stop the playback and again start playing the noise is again heard. Also the playback just freezes while I am playing and the DVD player application crashes. I have tried playing many DVD and again I experience the same problems. During playback of some DVDs the DVD player gives out the information that the disc is dirty or it is scratched and it stops playing. On physical inspection of the DVD I can see no such thing. I have tried audio CDs too and again I experience the same occurrences. Has the drive developed a defect? If so, will Apple replace the optical drive and what do you think will be the cost of replacing the drive with a new one. Thanks for you help. Any help appreciated.