Thanks for providing that information. Another thing that would be helpful is the log for the Editor itself. Could you please open your project and trigger the error message, then immediately close the Editor and send us the resulting log file? You can find that located at:
C:\Users\<your user name>\AppData\Local\UnrealEngine\4.4\Saved\Logs
You should see a UE4.log file there, and possibly one or more backups. UE4.log should be the most recent file, and is the one that we need.