I restarted my 2011 MacBook Air (Mountain Lion) this morning only to have it hang on the Apple logo for 10+ minutes. *I then attempted to start up in safe mode, no luck. I then zapped the PRAM but no luck. In fact, when I restart I now just get a grey screen (with no Apple logo). What really concerns me is that I am not able to start up with Command-R to simply start fresh. Any thoughts on what I might try? Does this sound as bad as I think it may be.