After I applied the most recent OS X update, my rev A MacBook Air become very very sick! My first problem was the battery - even in Sleep mode, the battery would drain itself. My second problem was a couple of systemwide crashes. I had to hard reset the machine and reboot. It happened on the Mac and Windows side (I use Boot Camp) My last problem seems to be related to the second. There are some occasions when I can't even boot into Mac or Windows. I've gotten the dreaded X on the Apple logo and other times the waiting icon spins and spins. So I took it back to the Genius Bar and apparently my hard drive needs to be replaced. It's possible the battery and/or logic board needs replacing too. The work will take 10 days or so. I don't know if the OS update caused all of this or if my machine just clunked out for some reason. I was a very happy camper up until a week ago.