I got a new 5k iMac (late 2015 27" iMac 3.3GHz 8GB (will add more), 2TB fushion, M395) just over a week ago. I was rather dismayed therefore that while I was using it the screen froze. I could move my mouse, but it could not do anything. I decided to wait it out (ended up being almost an hour in total). Sometimes the mouse pointer would disappear, sometimes it would be huge, and it stopped moving. The time also stopped changing on the clock. I left it for a while, when I came back the screen was black. Moving the mouse did nothing. I pressed the power button and it would seem it had probably been sleeping I couldn't wake it (since mouse / keyboard wasn't reacting). I forced a reboot. It seems to be okay now. I called Applecare and they just got me to delete some caches, etc. I didn't think of it until yesterday to look in the logs (the crash was two days previous). In the log during that time were several entries like this: 13:02:58.487271 -0500 DumpGPURestart com.apple.message.domain: com.apple.crashreporter.writereport.gpuRestart com.apple.message.signature: Kernel com.apple.message.signature2: UNBUNDLED ||| kernel ((null)) com.apple.message.signature3: UNKNOWN com.apple.message.result: noop com.apple.message.summarize: YES At the time of freeze I was attempting to switch applications via the dock. Certainly nothing intensive. I had been using Aperture to import some images (sorry I just can't like Photos app). So I realize there is a chance that (unsupported) Aperture might be to blame. I'm just concerned that it might be a hardware thing and I want to figure that out before my 15 days are up. Is there something I can do to check it out or should I just try Apple again? Thanks in advance.