I've tried booting to my original install CD and the macbook (late'08) continues to cycle between the black and grey screen with the start up tone each time. I've tried booting to it thru System Preferences, after inserting it and getting the menu to click to install, holding down the C , the M and Option. In every attempt the result is the same. I've started in Safe mode, reset Pram, SMC, verified disk and repaired permissions and tried 2 other macbook install CD's. Normal boot up is fine in all other cases, just not from an install CD. Any other suggestions out there?