Flash file with a mind of its own

I have a very strange problem. Or so it seems. I am making a website for someone using a Flash MX template. I converted the file to Flash 8. Everything seems fine. I am editing the file, changing text, changing symbol names, organizing everything. Everything is OK.
My problem seems to arise whenever I import files into the library or whenever I create new symbols. The files imported or the new symbols seem to randomly replace other symbols. And it doesn’t make sense because at first everything is fine. I publish the file, look at it, and its great. When I save the file, close it, and open it up later… thats when I notice that my background image has been replaced by the empty movie clip that I created earlier, etc.

Does this sound familiar to anyone?