Word has currently acquired a nasty trick which is really irritating. I imported a dictionary in Irish (Gaelspell), and added it through Tools/Options/Spelling/Add.

Now Word refuses to recognise lots of ordinary words in English - "book", for instance. I'm gradually adding them back.

The weird thing is that if you right-click on the underlined word, it's there in the choices, but sliding down to that choice doesn't work.

If you use F7 or Check Spelling, the word is shown in its capitalised version - "Book", for instance - but not in its lower-case ("book") version.

Still, at least I can type in Irish without the whole thing being queried.