I've always had problems shutting down my rMBP, I believe it's something to do with a shared network drive. On Mavericks I would select shut down, the top bar would disappear but it wouldn't shut down. I'd then load up Safari, select shut down and it would then actually shut down. It would also shut down on the second attempt without fail. Now, after upgrading to Yosemite at least 50% of the time it will not shut down and all and it often locks up (non-responsive) so all I can do is hold the power button to shut down or restart. Anyone else having this problem?