Windows Movie Maker Will Not Save My Video

I am having difficulties trying to save my video from the latest Windows Movie Maker. The video in the preview loads fine and the video plays fine, however, when I try to save the video, it gets to a certain percent and then says that it can not find some of the videos/pictures on my computer. I have not moved, edited the name, or deleted any of the files and they are all stored onto my computer, not an external drive. I also have updated everything including my video driver, and that did not work. I installed the certain codec that GoPro uses, and that didn't work either. I would like some help, because this has happened on my last two videos I have tried to edit.