My wife and I are getting ready to buy a house, but we have a major concern before we move forward. The house has a crack in the ceiling were the living room joins the dining room and also in the entryway almost adjacent to the first crack. I decided to check the crawlspace directly under these cracks and there is crack in the cement floor running almost the length of the crawlspace if I remember right. The crawlspace crack is just slightly more towards the front of the house. What might have caused this and how would someone fix it or prevent it from worsening. There is a big tree right next to the house, not sure if this could have cause this or foundation shifting, etc.