While you may have Track Changes turned off, there is a problem
associated with Heading Numbering in documents that previously had
changes tracked. Even after you have accepted all changes, inserting
new Heading Numbered paragraphs will result in the appearance of
Tracked renumbering. This tends to occur more frequently on documents
from older versions of Word that have been inflicted with spaghetti
numbering (see the MVP site for more on this). Sometimes the only
solution is to Paste | Special | Unformatted text the existing document
into a new document and then reformat.

There is also a Display problem associated with Track Changes and
Heading Numbering. In this case, you can accept a change to a Heading
Numbered paragraph and it would appear that nothing has happened. If
you scroll the changed paragraph off the top of the screen and then
back down you will see that the Accept Change has indeed been
implemented.

While not a solution, hope this at least provides a little bit of
insight.