Apple yesterday released iMac Software Update 1.2.1 (Tiger). The patch to the Mac OS X 10.4 Tiger OS is intended for 20in and 24in aluminum-clad iMacs operating at 2.0, 2.4 and 2.8GHz running Mac OS X v10.4 Tiger.
Recently Apple acknowledged a problem that can cause these models of iMac to freeze suddenly under certain circumstances.
On 1 November, Apple offered software updates for Leopard and Tiger users affected by the issue.
This update "improves the performance and reliability of graphics-intensive games and applications and fixes an issue that some customers encountered when installing Mac OS X Leopard after applying iMac Software Update 1.2", according to Apple.