HELP! windows movie maker wont save my video

It took me forever to make this video and it's really good. I need it done as soon as possible. So I downloaded all my files, edited it, added music and what not, and then I try to save it but it says, ---Windows Movie Maker can not save this file to your specified location. Verify that the original source files used in your movie are still available, that the saving location is still available, and that there is enough free disk space available, and then try again.--- Everything it says I have done. The original files are on  my computer. I have tons of free disk space. I have tried it so many times! Fixed anything that might work, but nothing happens! It's so frustrating, and I NEED this video. Any suggestions??