Apple has released a software patch that addresses a widely reported flaw in which iMac screens would freeze.

Early last month Apple conceded that a software update it had issued caused some iMacs to freeze during use. Apple's own website notes on the update say only: "This update provides important bug fixes and is recommended for 20-inch and 24-inch iMac models with 2.0, 2.4, or 2.8GHz processors."

The 1.1 update affected the ATI Radeon graphics card used in the computers, causing the screen to freeze-up, leaving users with a useless Mac, until they force restarted the machine.

Two versions of the update are available, one for Mac OS X 10.4 'Tiger', the other for Mac OS X 10.5 'Leopard' systems.