I'm having problems with my mid year 2007 MacBook Pro, I did a clean install, but now it won't recognize any disks, after I install XP. I want to reinstall Ubuntu, OS X, and 7, but it won't work from either USB or CD. Can someone help me?
Your optical drive could be failing, but that doesn't explain the USB not booting. Have you reset the PRAM/NVRAM? If you put a bootable media in a USB port or the optical drive, then hold down option during the startup of the Macbook, does the media show up at all?