Once in a while car dies while trying to start

every once in a while when i try to start my car .. when i turn the key i get a big clunk and everything goes dead in the car.. interiors lights and everything are dead.. then i wait a few minutes or if i just touch the battery or shake the car the lights come back on.. then i turn the key and it starts right up.. i changed my alternator a few months ago( had it tested and was advised bad alternator and battery was ok) need help.. not sure if its a short or something.. happens about once or twice a month.. the interior lights kinda pulse when driving a little..