MS Word's grammar checker continues to annoy me. Today it seems to have a particular peeve with split infinitives (I suppose the problem could be that I'm splitting more of them than usual).
When I was a summer associate at the New York office of White & Case many years ago, one of the partners for whom I did a lot of work handed back a draft memo on which I had spent a great deal of time and asked me to spot and fix all the split infinitives. Being a cheeky lad, I sent her a xerox of the relevant page of The American Heritage Dictionary of the English Language, which states:
The only rationale for condemning the [split infinitive] construction is based on a false analogy with Latin. The thinking is that because the Latin infinitive is a single word, the equivalent English construction should be treated as if it were a single unit. But English is not Latin, and distinguished writers have split infinitives without giving it a thought. Noteworthy splitters include John Donne, Daniel Defoe, George Eliot, Benjamin Franklin, Abraham Lincoln, William Wordsworth, and Willa Cather.
Surprisingly, I nevertheless received an offer of permanent employment, which I ultimately turned down. In any case, I shall continue splitting as I see fit.