Apple offers fix for iMac's Radeon HD 4850 freezing issues
A rare weekend software update promises to cure system freezing issues in early 2009 iMacs equipped with an ATI Radeon HD 4850 graphics chipset.
It also mends problems owners have encountered which prevent the systems from waking properly from sleep when using Boot Camp, Apple says. The update requires Mac OS X 10.5.6 or later.
The company hasn't explained what has caused the problems, which have triggered lengthy discussions on Apple's support forums and, though producing different symptoms, have drawn parallels with an earlier ATI graphics freezing issue from 2007.