Problem: if one Restarts (reboots) iMac 2015 running Sierra 10.12.5 when Mathematica 11.1.1.0 (re-open windows when loggin in default is YES), Mathematica opens white windows and one of these windows is grey and has a spinning dial (not the ball, like the dial pdf uses). The names of the (one or few) notebooks are correct, but they never show text (are white) and the time dial never stops spinning. I've had this same issue on all updates of Mathematica.

Poor answer: Quit Mathematica, re-open it. This of course bad because it means one cannot Restart their OS without treating Mathematica specially on logout - and if they do not, then are forced to deal with it after any Restart.

I've seen this or similar problem posted as "solved in next release" and "solved if you take this extra step" by (wr employees). See below: I tried all of them and none had any effect whatsoever.

Let's be clear by today's date one can still not Restart without dealing with Mathematica "freezing" issue. I'm at the latest Home (11.1.1.0), and latest Apple Sierra (10.12.5) update.

These, by being vague, indicate a same or similar problem: but following their answers has no effect whatsoever:

http://community.wolfram.com/groups/-/m/t/559823

http://community.wolfram.com/groups/-/m/t/904428

http://community.wolfram.com/groups/-/m/t/1093145