Hi I am hoping someone out here might be able to help and end my frustration. I bought 12 Working Macbook Computers off of a client of mine. All of them were in excellent working condition but the hard drives were wiped. In the past, I would make a bootable USB of OS X and install it and everything would go great. When I am trying to do that today, I keep getting the File Folder with the ? And then the Prohibitory Sign. I have tried installing both Lion and Mountain Lion. Based off the serial number this model should be able to support those as it is a 2007 Model. Can someone please offer me some help or advice on how to get these up and running. Thanks!