Well, we've fixed it, but I don't know for sure how. I noticed that her page
numbers were not showing up, that it was showing the page number field code
instead. So I went to Tools > Options > View and unchecked the Field Codes
box. This fixed the page number problem and from that point forward, the
Track Changes started to work again as well. I have no idea why the Field
Codes box being checked would affect Track Changes, and I can't recreate the
problem on my PC.
A lot of the settings in Tools > Options are changed from the default.
Something happened to her settings over the weekend that changed them all.
And now she's having another problem: when she's inserting a hyperlink into
an email in Outlook, it again shows the field code instead of the hyperlink.
But when she goes to Tools > Options to try to uncheck the Field Codes box,
it won't allow her to make a change. When she hits OK, an error message
comes up saying, "Number must be between 1 and 1638." Something very weird
is going on. I'm going to see if our IT people will just reinstall Office
and see if that fixes it. You might try the same.