I work at a retail store and we are an Apple certified reseller. As such, we have floor demos of all current models. Funny thing, we've not yet received a fully functional 27" 2011 iMac to demo. We've gone through 2 dead-on-arrival units, both actually experiencing the same issue. Once loaded, they could not connect to the local wifi network, and after anywhere from 10 seconds to 20 minutes they would freeze, locking the entire computer until a hard reset was performed. Each had issues connecting to a network which every other demo we have ever had has connected to, and each continued to freeze, consistenly, after a hard drive wipe and OS re-install. Has anyone experienced this? The first call I made to AppleCare took a solid hour even AFTER the OS re-install to get a confirmed DoA, but the second model took 10 minutes, tops. Is that because it's getting more common or I'm just better at explaining why my computer won't work the second time? The second one actually had a grey screen with a power icon pop up that said a hard reset was required in several languages, which may have also helped my case.. but even then that was only one of about a dozen times it locked up on me..