Quite possibly the worst problem Scotland has and the most difficult to solve. Centred around but not restricted to the rivalry between the two big Glasgow football clubs, Celtic and Rangers the problem goes back to the tensions between Catholics and Protestants and emigration and immigration between Scotland and Ireland. Ultimately the problem still exists because of poverty and competition for limited opportunities - pretty much the same reasons as any ethnic, tribal or religious conflict anywhere in the world. A better standard of living for all would go a long way to solving it but it's going to take time, a lot of time.