I downloaded the latest Mac version of Minecraft (1.4.6) on a 27" iMac 2012. When I launch it, I get ' "Minecraft" is damaged and can't be opened. You should move it to the Trash. ' I've downloaded it to a Retina MBP and 2010 Mac Pro. Both launch it just fine. Both are running the latest OS X Mt. Lion. Any ideas as to why the 2012 iMac rejects it?