Oh my, this has annoyed me more then stupid people in Saw (which I also watched this weekend) An American Haunting is a tense and very well crafted horror movie until the last 25 minutes and which point it falls apart in the most spectuacularly shit fashion possibly imaginable.
If you intend to see this film, leave right after the wife has a vision and use this ending instead;
As a boy Donald Sutherland was playing in the forest with the little ghost girl and accidentally killed her before the body was consumed by a wolf.
This spirit manifests to extract revenge on Donald Sutherland and his youngest daughter with who there is a close resemblence.
Please, really if you should have the fortitude to stay to the end you will regret that this ending did not occur.