GoPro Support, I hope you are listening to the feedback you are getting from this problem. There have been a couple of updates since this thread started and still the error message users are getting is not helpful in identifying the problem. (I would guess there is an error writing the file for some reason.) Although you must know what the trim function does in terms of what files and folders should be used/created you have not managed to diagnose the difference between working and non working installations, this all looks distinctly amateur.
Personally I'd prefer to be using Windows for the apps but they have stopped working on Windows 7.
While trimming is also possible in Quik, you might be getting more than you want, like the original sound track overwritten by music, by default at least, options could be clearer.
