As in the question above I am unable to 'quit' Lightroom CC in the normal way on my iMac. I think this happened after I ungraded the operating system to OS X EI Capitan. I would appreciate any ideas as to why this may be happening.
Photoshop CC (2015) appears to run and quit as normal as do my other applications.
First, see if the Mac 10.11.1 bug fix update will help you
-some discussion of 10.11.1 https://forums.adobe.com/thread/1986008
-ALSO need to update the nVidia drivers (links included in message)
-there is also "some" mention of a further 10.11.2 bug fix being tested by Apple
There are known problems with Mac 10.11 El Capitan... that may be one of them
See reply #5 in https://forums.adobe.com/thread/1965850 for several solution links
-the first link in that reply is a possible solution to install problems
-there is also a link about video display problems in Premiere Pro
-and several other programs... PLUS Microsoft Office also has problems