OmniDiskSweeper has messed up my machine (my fault, admittedly). It's missing tons of software and deleted pretty much all of my Utilities folder plus about half of my applications. Basically, I need to start over. The problem: my MacBook refuses to boot any CDs. I have my iMac install, my retail leopard install, and my MB install disk. When I hold down D or even do the option to bring up the disk selector, the screen goes black and reboots. What might be wrong?