I can't boot up using my mac osx cd when i'm trying to install a new hard drive (my old on crashed), i've tried holding down the C key, but that doesn't seem to work. I'm also using a USB dell keyboard, i don't have the mac one, Ok, the alt - windows - P - R worked, i continued to hold them and let the chime ring 2 more times, then i released them and began holding down the C key. The CD drive started up and the screen was gray, then the screen blinked and went right to the question mark and apple logo. I held C down the whole time, could there be an issue with the drive? Don't know why it all of a sudden won't work anymore. I can't boot from any CD now.