I just posted an analysis of the problem on my system over in the Windows section:
http://duc.avid.com/showthread.php?t=406849&page=12
See if this applies to you. I think this is a complicated memory allocation issue that in my case involved a Command|8 midi controller and large sample libraries. It also messed up font scaling with 4K video.
Perhaps this will give you some clues. I have a workaround for now on my system.
ejinbc