I have a 2007 Blackbook with Snow Leopard installed. I tried to install Bootcamp but it said that I had to do an erase + reinstall first. I booted my mac up from the OS X disc, got past the language menu, then got a pop up stating "MAC OS X Cannot Be Installed." I can't click on Disk Utility or anything else on the menu bar. How else can I erase my HD?