This has happened to me many times. I start producing a video, and when it is done after 10-20 minutes the file is either really small (couple of kb) or it has only produced part of the movie even though I saw it fully run in preview mode.

This means I have to produce the same thing again and hope it will make a full movie this time. Why is this software so buggy? The software is amateurish with its advertisement popups, disappearing video files, and pixelation when using fast video rendering. Luckily they fixed the constant crashing from earlier version ...