I'm having problems w/Movie Maker, where it shows the same thumbnail multiple times, so I cannot edit the project/movie.  (I've used it before w/o having this problem.)  It's now happening on my "projects" and on all MP4 movies (that I've tried).  (Screenshots below w/descriptions.) 

I'm a novice at MovieMaker, but have not had this problem before.  I've uninstalled & re-downloaded Microsoft Essentials, and rebooted my pc. The same thing now happens with both my projects and w/any MP4 movie I've tried. :-\  (???) 

Examples:
"Project" (1) - Showing 1st shot of movie on left, after I set start & end points and trimmed twice. (Last trim was up to the shot that is now the repeating thumbnail, from 1st line on 'til end of thumbnails.) ~

Same "Project" (1) - Advanced video to the shot that is now the repeating thumbnail ~ 

Same "Project" (1) - Advanced further into video, still showing same thumbnails on right, with all but top line* of storyboard being the same repeating thumbnail *(not shown in this screenshot) ~  

MP4 Movie (2) - Showing 1st shot of movie on left, with same shot repeating multiples times on right ~ 

Same MP4 Movie (2) - Advanced further into film, still showing 1st shot as repeating thumbnail ~ 

I don't know what to do....Help!!!

Thank you,
Meg D