I added my photos and video clip to my project without error and saved the project OK.  When I try to save the movie as an MP4 file for high def display it starts the process but part way through I get the error.  I reviewed the project and removed the indicated file(s) and tried again.  Each time I get the same error and and files that were previously OK now are indicated as being the problem.  This is a large project with almost 900 pictures and 1 video clip; is there a limit to the number of pictures I can have?