Is this in .doc format and are you opening it with Word 2010 or later? We had a company template I created especially for handling Word files from several sources with possibly conflicting styles. The template styles were based on "no style" so that they could be applied without conflicts. It worked fine for years, but in Word 2010 it started acting crazy. One style ("bullets," I think it was) would change on its own into Heading 3. It's possible that certain styles from a Word doc will be unstable in docx.