Why do the hazard lights come on in your Land Rover Discovery after driving over corrugated roads?

Most likely your alarm ecu has broken loose from the mounted position, if its loose and gets knocked around. It will turn on the hazard lights, thinking that you have had a impact related to an accident. Easy check remove the trim panel below the glove box. and look for a green box maybe 1" thick by 5" long. give it a wiggle and see if it moves. If so simply get some zip-ties and strap the box down so it cant get knocked around.