Words replaced by a square and "tala"

[Makiki]

I've run into a strange problem in one of my Word 2002 documents. Sometimes
when I open the document, I'll find that certain words have been replaced by
a square and the letters "tala" or "talag." I'll correct them and save the
changes, but sometime later they'll revert to that odd sequence.

Does anyone have any idea what is causing this and what I can do about it?

Thanks.