A few minutes ago Apple released a firmware update for the Mid-2010 21.5-inch and 27-inch iMacs. The update – a 767 KB download – aims at fixing hard drive issues that prevented some systems from booting properly. My iMac surely had this problem – especially after installing Lion on a second partition, I noticed several booting issues that this update will (hopefully) fix.
Go download the iMac Hard Drive Firmware Update 1.0 here.