Were these documents created in Word using one of it`s templates? e.g. on another computer or version of word. If so the easiest way is to get a copy of that template and transfer it to replace the newer one.
I`ve only ever had this problem, with about 250 files when I changed from Word 4 (I think!) to Office 97 and I changed every one as I had to use it again. It should be much easier now and I found this click here Scroll down to "Where do styles come from" - it gave me a few ideas but whether it works with HTML templates I don`t know.