One more thing: Like Kdenlive, OpenShot is just a GUI on top of the MLT engine which provides the actual video editing functionality. (It's very much comparable to how Webkit provides the engine for a number of different web browsers.) Since I have never experienced a program using MLT to be stable, I wonder whether the instability is actually caused by MLT rather than OpenShot itself. MLT has been in an experimental state for many years. Even if OpenShot provides a great GUI, it can only be as mature and reliable as MLT is.