Apple today released an iMac Firmware Update 1.4 to resolve some outstanding issues with certain models freezing and another issue with Bootcamp, Apple’s technology for allowing users to run Windows on Mac. According to Apple’s documentation, the update fixes intermittent system freeze issues for iMac computers with ATI Radeon HD 4850 graphics and fixes wake-from-sleep issues in Boot Camp. Readers report that the iMac freezes occur in a wide variety of applications—and even when not running Mac OS X (such as Bootcamp) and that typical troubleshooting steps do not resolve the issue.

Users much follow the follow the instructions in the updater application (/Applications/Utilities/iMac EFI Firmware Update.app) and the updater will launch automatically when the Installer closes. After the firmware is successfully applied to the iMac, the Boot ROM Version will be: IM91.008D.B08.

source:macnn