Ok so today I created a new project using Unreal 4.8.1 and created a new matinee (Trying to figure out how matinee works) and I took the matinee editor tab and placed it in full screen on my second monitor so I could see what I was editing. After I did that I created a new camera folder in the matinee editor. However if I click on anything that is not associated with the matinee while the editor is open the game crashes with no crash report. The Matinee editor tab closes out then Unreal freezes for about 30 seconds then dissapears.
P.s. I have not tried recreating this with other versions of Unreal.
Thank you for the report. This looks to have been reported and is currently under investigation, for reference UE-17162. As we work toward a solution, I will keep you posted here.