Jags

Hi,
I am using Vista Home Premium. I have created a movie with Movie Maker, and
when i try to publish the movie with the default settings, its giving an
error message: "Movie Maker can not publish the movie. The source files may
not be available, or the disk space is not enouth...". I have my source files
in the same path, 50GB of free disk space is there. But its not publishing
the movie. But, if i select the third option the select bit rate window ie.,
AVI-DV in the dropdown list, the publishing is successfull. But the .AVI file
created is huge in size.
Can anyone tell me what is wrong with movie maker, and why it is not able to
publish the movie with default settings.
Thanks and Regards...