New iMacs Emulate Windows with UI Freezes
A growing number of users have reported that Apple's aluminum all-in-one computers suffer from a flaw that locks up the interface, rendering the system all but inert until a reboot.
The issue appears to be related to the ATI Radeon HD graphics hardware and its drivers, but has proven unpredictable. While some customers have said they can reliably trigger the freeze by running games, iTunes, or other programs that push the video chipset, others have had the lockups occur at seemingly random intervals or after running the iMac for a long time.
But, but ... those Apple vs. PC commercials said only the PC would lock up! Yeah, right. Indeed, this sounds like some sort of driver issue, but it would be clearer if all the lockups occurred during some sort of hard video use.