“Sorry, Movie Maker can’t open this project file. The file might not be compatible with Windows Live Movie Maker or be corrupted.”

Help....  I have spent weeks and weeks on a movie project and was on the final stages when (out of the blue) the above message appeared.  Now I can no longer access this file.  All has been working well up until this point.  I had been able to open, close, save, add pictures, add music, etc and all was working fine, until yesterday, when this message popped up. 

"Sorry, Movie Maker can't open this project file.  The file might not be compatible with Windows Live Movie Maker or be  corrupted."

 I have made other movies using this program and, fortunately, I am still able to access and play these (thank goodness), but just can't access and finish my current project.    I am desperate for someone to help me save this project.

JMM