Sounds very strange, something's obviously spooking her. I think I'd be a little hesitant about trying to change her behaviour until you've found the cause, - you could make the situation worse. How old is she? Has she got any problems with eyesight? HAs she always been the same?,We went hiking today and suddenly it started to rain, one of our group put on a rain cape on and Humphrey went ballistic and started barking quite agressively- ) Sometimes it can be seemingly insignifant things that can spark off,,what seems to us as, strange behaviour. I would try and observe here closely and attempt to pinpoint the exact moment when the behaviour starts and see if you can determine what has changed, does your house or visitors cast shadows for example? Its a hard one......! Good luck, - keep,us posted!,