So, I'm sitting here replying to an email in the Mail app when suddenly my mailboxes start loading up with "new" emails - more than 5,000 of them! Turns out, they are emails dating back about 2 years that have somehow suddenly been redownloaded. I tried quitting Mail but it's completely hung. Looks like a force quit is in order. ML is pretty much crap. I wish I could go back to Snow Leopard. Best OS Apple has ever released, IMO. Mac Pro, 12 core.