Weird symbols replace user names in Track Changes comments

Hi, I use Microsoft Word's Track Changes feature, including the comment function, nearly every day. Sometimes I receive docs that have been edited using Track Changes, sometimes I use Word's Compare function, and sometimes I edit using Track Changes. The following problem does NOT seem occur to occur in the latter scenario (unless the problem has already occurred, in which case it continues). This problem started occurring out of the blue...

When I receive an edited document or perform a comparison, the user names are replaced by wacky symbols that remind me of the Wingdings font. The comments themselves, the original text, and the in-text edits appear unchanged. This also appears to happen regardless of where the documents originated or of who worked on the documents before me.

I took a screen shot of the problem and posted on an ancient blog of mine, here: http://the17pointscaleappendix.blogspot.com/2011/01/microsoft-word-is-evil.html.

Thanks,

Andrew