I finally upgraded from my 2011 MacBook Pro to a 2015 13" rMBP. I've had my new one for about a month, and I noticed that it started to hang or freeze up as I shut it down. I had this issue on Yosemite, but when I upgraded to El Capitan, it went away...for a little while. It started happening again about two days ago. I've never had this issue on any other Mac, so I'm pretty sure it's not normal. I've only found one other thread with something like this, and they didn't find any solutions. I've reset SMC, PRAM, and nothing worked. The closest Apple Store is like 60 miles away, so I want to know if anyone thinks if it is some kind of defect, or if it is bad for the computer. Thanks. Here is a video of my issue: Also, on a totally unrelated matter, upgrading to El Capitan pretty much eliminated any UI lag that I was experiencing while scrolling through the web or switching apps.