my 2 1/2 year old G4 iMac will no longer read DVD movies or music cds. when a disc is inserted, it spins the disc around for maybe 10 seconds, makes a few quiet, quick 'purring' sounds then ejects the disc. however, it will still recognize and respond a blank disc. for last little while it would only do this if the computer had been on for a long time but now it does it even after a good night's rest. any ideas or help?

1) Log in as a different user and verify that you can no longer get commercial CDs/DVDs to mount there.

2) Try a CD/DVD cleaner that you might use in a regular CD/DVD player.

3) Try zapping the PRAM & resetting the NVRAM

4) You may have to have it serviced, hopefully you have AppleCare.

activate your root account (start with OSX-install Disc/changing passwords)
restart regularily, switch user to root. having done so, every volume will be visible. on the dvd do an æ-I. change priviledges to allow everything. log out to
your regular account. Your DVD is back/mounted.