A strange one... I have an early 2009 iMac 24" 3.06 Ghz, still running just fine with one exception. The optical drive will read and write cds, but does not like any brand of dvd and ejects them. Will not even accept a commercially produced dvd. As a result I connected an external dvd burner and it works just fine so I am assuming that it's not a software issue, but some issue with the superdrive itself. Any thoughts on the subject will be appreciated. Thanks for looking.