As much as I like Word, it really does cause a lot of headaches for everyone that uses it and through them, me.
Latest issue that's popping up...Word documents with some words or all the words set to a language other than English - US, such as French or Spanish.
This really screws up the spell checker, as you might imagine and it's not exactly intuitive on how to fix it (hint, you can't change the language setting through the spellchecker).
Select the whole document, go to Tools->Language->Set Language->select English (US) and select OK.
Now the question that I have is this, if the normal.dot is set to English (US) why would Word ever change the language of a document based on normal.dot.
I don't know, maybe these sorts of "features" creep into Word and cause problems because the Office team is giving users what they want instead of what they need.
What my users need is a word processing application that always works and that does EXACTLY what the user wants it to do, when they want it to do it, nothing more, nothing less. Word is generally stable, but fails on the second parts. WordPerfect seems to do better on the second parts but fails horribly when it comes to stability (pro viso for this is that I have used WP 8, 9 & 10).
Unfortunately, Microsoft is pretty much now the only game in town when it comes to word processing.