Sometimes if I try to open Dorico only the name ‘Dorico’ appears, but nothing else. (Please look to the attached screenshot). I use OS X 10.11.6
That is indeed very strange. You say “sometimes” - how intermittent is it?
Could you tell us a little more about your setup? e.g. Processor, RAM, SSD?, connected USB devices such as audio interfaces, MIDI devices, etc.
I had this about 4 or 5 times and I opened Dorico overall perhaps 20 or 25 times. I use a MacBook Pro (summer 2012), 2,9 GHz, Intel Core i7, 16 GB 1600 MHz DDR3, no SSD. Probably I had always a second monitor connected when this bug happend. But no USB devices such as audio interfaces, MIDI devices, etc.