Windows Movie Maker - Codec not installed???

Ok, so I made a picture slideshow - I uploaded it into Windows Movie Maker once and all was fine.  A few days later I started getting an error saying that codec is not installed - what is up with that???

 

Dell installs several codec programs - and none worked.  Their final decision?  Reboot system to factory settings!!!  Still nothing - I can even make a slideshow in Windows Movie Maker - and safe it, but it will not open the file back up saying "no codec"

 

Can anyone help?????