Even when you explicitly set Microsoft Word to French and attempt to type in that language, it sometimes mysteriously reverts back to English in part of the document and then gives you a case of the red squigglies.

I am not as good at French orthography as I am at English, so I spent like 30 seconds staring at “parfois” trying to figure out what the hell I’d spelled wrong because it looked fine to me.

It was fine; Word was the one with the problem — surprise!