It seems that UE 4.3.1 crashes when loading a level that has a matinee it with animated cameras and a director track. The crash happens if the matinee actor has “play when level load” enabled. Its hard to always remember to disable that option before closing the editor 
Hello Schmidt,
Although it has been some time since your original post. We would like to follow up and make sure you have been able to work around your issue. Currently we have moved to version 4.6 which contained a lot of great fixes and features. Try updating to a newer version of the engine to see if your crash is resolved.
If you are not able to update for some reason, or have update and are still experiencing your crash, let us know and we will further investigate.
Thank you,