Apple customers who have recently purchased a new, customized aluminum iMac containing the ATI Radeon HD 4850 graphics chip have been experiencing lockup issues. The issues surrounding the recent reports seem to duplicate reports from nearly two years ago when a refreshed line of iMacs exhibited hardware issues relating to the graphics chipset interface. Apple later released a firmware update to correct that issue. As of the writing of this article, no firmware update or other fix has been officially released by Apple.
