Just a comment on this, I was getting a pop-up dialog in 2 completely different projects that read “Fatal Error!” whenever I would switch levels. Going into the log file I found that the fatal error was a result of an error in the AudioMixerRenderThread(1). Both of the projects were made with the engine version in which I used gigahest’s solution. After reversing the changes back to the default, I no longer received the Fatal Error messages.