Bought a Late 2013 MBP and want to do a clean install of Mavericks. First I am unable to download Mavericks from App Store, error message stating does not meet requirements. I do have a USB Drive of the installer, however when I attempt to boot from it I get an gray screen with an X. Any suggestions? Attempted to contact Apple Care and they stated I couldn't install because the machine is already running Mavericks. I understand that but would like to install from scratch.