I am looking for the name of a movie I saw in the 80"s. It was really scary. It was 2 or 3 people stranded in a house in a snow storm. There was an old man and a player piano. At the very end the hero figures out that the old man's pacemaker was setting off the player piano and that's how she know he was the bad guy. What is the name of this movie?

Thanks MBG

Dead of Winter (http://anchorwomaninperil.blogspot.com/2008/01/dead-of-winter.html)