Help with a Title

Hm. Have we addressed this?

For some reason, I'm having trouble changing the title of a post, because MT has identified the post as X, and in MT's mind, X it will remain until the end of time.

What I did was use standard title style, except that the word "is" begins with a lower-case i (I was typing too fast; I must have unconsciously thought the word was "in," a preposition that should be lower-cased). So I tried to edit the post, but MT has this mind-block and just won't do it. I even tried rebuilding the whole shooting match. No go.

Any thoughts? It's such an odd little thing to happen.