Is there a place that's up high enough for her, perhaps a really tall cat tower or a series of shelves arranged in the manner of stairs that she could climb, preferably near a window? I can recall Jackson saying that cats are either cave dwellers or tree dwellers, at least I think that's the term he used. Anyhow, my point is that she's hiding in the litterbox b/c she feels safe there. If you give her a spot where she can be up really high away from everyone and that enables her to look out the window, she may be happier. Just a thought.