Issues saving the Movie Maker file to MP4 format in Updated Anniversary Edition of Windows 10.  Computer is very slow, it takes hours to save.  After waiting for this I often get unable to save due to corrupt files I have to remove.

Once saved, the video looks horrible with flashing lights throughout.   Video views perfectly in Movie Maker and from video file.  I can upload to Facebook with same results.  Once I save it to upload to You Tube (MP4 file) this is when my trouble starts each time.  

I have tried saving to different formats, using custom bit rates etc, uninstalling Windows Essential and reinstalling, checking for graphic updates etc and I am not able to fix this!

Please help!