I just installed of Tiger -- the first time I've ever done a 'clean' install of any OS on my 600MHz iBook -- and it fixed my dead combo drive! My iBook originally came with OS9 and 10.1 installed. I have upgraded the OS before, but never a clean install. About a year ago my combo drive started to act up intermittently (for no apparent reason), and eventually it stopped working completely. In fact, I had to use the computer with the drive tray open all the time, because if you closed it the finder would get fixated on trying to mount the optical drive (which showed no other signs of life), and would hang the computer until you popped the drive tray open with a paperclip. Apple told me I should consider buying a new computer, and when pressed quoted me "around $1000" to replace the optical drive (if you can believe that). I'm glad I didn't, because it seems to have been a software problem after all. As I now have an external HD, I was able to back up my /Users/ folder and do a clean install of Tiger (which was a little bit of a trick with a dead optical drive). Now my combo drive works just fine, and so do my screen brightness keys, which had also become intermittent. When I first started having troubles with the combo drive people suggested repairing permissions, etc, but with the way the drive was acting I was sure it was a hardware problem. I have a new respect for giving a computer a good enema with a clean install!