Owners of new Apple iMacs, equipped with an ATI Radeon HD 4850 video card, are reporting problems with freeze ups during normal usage, forcing them to reboot the machine. The problem doesn't appear to be caused by software running at the time of the freeze in Mac OS X, and some users have noted that the problem persists using Windows in a Boot Camp partition where drivers or Mac software wouldn't be an issue.
This isn't the first experience of this kind of problem for Apple systems. In March, some users of MacBook Pro machines reported graphics issues during use, related to the NVIDIA 9600M and 9400M GPUs. Back in 2007, when the aluminum iMac machines launched, another freeze issue surfaced. That time, it allowed some programs to continue running, whereas the latest issue freezes up the entire system.











