Long story short, I had to wipe the internal HD on my 2012 Macbook Air, including the recovery HD. I tried twice to boot to Apple's Recovery Console (using Command+R), but it failed both times with error 2003F. Apple phone support had no idea what that meant. Wow. Anyway, I tried booting from an external HD that has Lion installed from a corporate disc image. It's not an install disk, it's the actual installed OS. All I get is the empty-set symbol (circle with diagonal line thru it) when I choose the boot device. Nothing works. I also tried booting from the "Recovery HD" on the external drive. I'm now going to try booting from an external DVD drive; I'm not optimistic. Any suggestions? I'd rather not hike back to the Apple store.