I hear that a lot, but I don't understand it. You're the person in charge... if your characters won't behave, fire them and bring in a new batch!
As for me, it's my mind that seems to have a mind of its own. It doesn't want to write the story that I have meticulously plotted and outlined... it wants to write the story that I haven't plotted, outlined, or developed characters for. I have no idea where this story is going, but it's really easy to write at the moment...
Argh! I'm drawing a blank on the folk song (was it James Taylor?) about a man named Bill who wouldn't get the cat down from the tree...