Was the doc originally created in Word?  Were the footnotes created using
Word's Footnote feature?

Do a quick test for corruption:

The first way to check for a corrupt document is to
copy the entire thing, *excluding* the last paragraph mark, into a new
document. That last paragraph mark holds a lot of information which can get
corrupted, and copying the text into a document with a fresh one keeps your
formatting, but can fix some glitches.

A paragraph mark is a ¶.  Click on ¶ on the standard toolbar to show
nonprinting characters, including paragraph marks.

See this link for further fixes:

http://www.mvps.org/word/FAQs/AppErrors/CorruptDoc.htm