Question about bipolar disorder.. serious answers please - i think my neighbour is a psycho!?

Well professionally speaking from what you wrote I doubt that she has bipolar disorder. It sounds more like an adjustment disorder if anything. She recently moved in and you were nice to her so she probably see's you as a comfort zone, a friend. She may just not be a very "socially inclined" person lol. But its hard to find anything out without actually talking to her myself. But it doesn't sound like bipolar disorder.