I have a 2008 MacBook Pro that was running Win 7 natively (no bootcamp). I wanted to install Yosemite on it so I made an image of the OS with a USB. I can't boot into the USB, all I see is the white screen and none of the key combinations work. I am able to boot into a CD and was able to install Ubuntu but it seems that the issue still persists. I've tried numerous things to get the boot loader back to stock but I can't seem to make it work. I was thinking of getting a smaller, older OS X ver that is able to fit on a CD/DVD and try to install that. Any ideas would be greatly appreciated.