Why am I having while saving my file as a movie file in Windows movie maker?

I am having this problem while saving my project as a movie.
When ever I am trying to save it, a message is being displayed that – “windows movie maker is unable to save this movie as the original files used in this file are missing, or the destination file/folder isn’t ound, or there is less disk place available on the destination file/folder.”
But none of the possible reasons are possible as I have checked all these possiblities.
PLease help me out..