Apple just released a new set of EFI firmware upgrades for all 2011 Mac models: The mid-2011 Mac mini, mid-2011 MacBook Air, early 2011 iMac, and early and mid-2011 MacBook Pro. The updates mainly contain big fixes, and improve the stability of all of Apple’s latest Macs.
Each of the updates addresses the same issues:
This update improves the reliability of booting from the network, addresses an issue that can prevent HDCP authentication after a reboot, and resolves an issue with boot device selection when a USB storage device is hot-plugged.
The updates are available immediately through Software Update, or by visiting the following links on Apple’s Support site.