We've had several folks let us know about an apparent problem with the new iMacs, both in post comments and by email tips. There has been an Apple Discussions thread about the issue, which involves random freezes in the new iMac. It apparently causes the interface to completely lock up and requires the user to perform a hard restart to recover. Macworld is reporting that Apple has now admitted that there is a problem. An Apple spokesman told Macworld that they are "tracking down the root cause of this bug, and will issue a software update which corrects it as soon as we can - most likely later this month."
AppleiMac 27-inch with Retina 5K display (late 2014)