What 90's horror movie has a robot living on ceiling in house and turns evil?

I've been looking to find the title of this horror movie for years. I'm destined to figure it out! Here's what I know:

A family living in a large house decides to install a helper robot. It lives from the ceiling and moves around on some sort of track system. Something happens and the robot turns evil. I remember one scene, when the robot is starting to get really evil, and the woman dropped her ring (I believe) in the garbage disposal. She almost got her hand taken off, because the robot turned it on.

It originated in the 1990's, possibly late late 80's It was aired multiple times

I gotta find this movie guys! Please help me out :)