In a post on a message board, when I used the word when I typed de-incentivised it was underlined by the spell-checker in spite of being a perfectly good word and the suggested alternatives were
e-incentivised, none of which look like real words.
But it got stranger. When I posted a humourous aside mentioning this fact, all of these suggested alternatives were also marked as wrong, in spite of being the very things the spell-checker told me to use. Intrigued I probed further and the suggested list of alternatives for these words included
none of which got underlined but most of which don't look like real words to me either.
I love spell-checker!