I've had a problem several times in the last week when my new retina MacBook Pro will shut itself down while sleeping. Basically I will leave it while I'm at the office, and when I return I'll open it up and expect it to wake from sleep, only it won't. When I press the power button, it boots up as if it was shut down (it does not boot from the safesleep mode that happens when the battery runs down). I suspect it's a bug with PowerNap where it crashes while it tries to do things while sleeping. Has anybody experienced anything similar?