I want to boot from my USB drive to install a fresh copy of Mountain Lion 10.8.4 on my new Macbook Air. I downloaded the latest version from the MAS, restored the "Install ESD" image to a USB3 thumb drive, and tried to boot from the USB drive by holding down the option key on my MBA. The first strange thing is that it lists the USB drive as "EFI". I seem to recall that the volume is labeled "Max OS X Install ESD". Anyways, I choose that option, and then the circular symbol with the diagonal line appears. I tried booting from the USB drive on my 2011 MBP, and it worked fine. It's just the MBA that's having trouble. Why is this?