I have a MacBook Pro (1.83Ghz) running Mac OS X 10.5.7. The optical drive makes sounds like it's accessing data off a disk. However, the drive is empty.
The sound is intermittent. Sometimes I won't hear it for a few days. Then the sound will start and may continue all day.
Things I have tried:
I reset the PRAM by rebooting and holding down cmd-option-P-R
I tried to download the most recent firmware and Apple does not appear to be supporting the 1.83 Ghz MacBook Pro any longer as there have been no firmware updates in the last year.