Apple Posts Fix for iMac Freezes
Apple said the update is recommended for 20-inch and 24-inch iMac models with 2.0 2.4, or 2.8GHz processors. iMac Software Update 1.3 (Leopard) and iMac Software Update 1.2 (Tiger) are available from Apple's Web site.
Apple acknowledged in early October that a software update it issued caused the computers to freeze. According to users the iMac became unusable, requiring a hard reset in order to recover.
Apple said it is encouraging its customers to install the update via the Software Update mechanism or the download link.