Movie File Won’t Save

I made about a 30 minute video.  I put every image and video I wanted to use into one folder on my computer.  After everything was finished I clicked save movie. It goes through the process of converting the video, but after waiting 30 minutes I get an error message saying there may be a missing codec, the files are removed, or something else that doesn't make sense.  I checked to make sure all the pictures and videos had the right file format and they do.  I made sure I had the lasted version of movie maker. Also everything plays fine when I first open the file in the player, but after I try to save it and waiting for 30 minutes, the error messages come up and the file won't even play in the movie maker any more. I need a solution.