Is this house going to collapse?

My in-laws live in a really old house (around 100 years old) and there are a lot of cracks in the walls downstairs. Some of the cracks look to be in random spots in the upper half of the walls. Every doorway or opening to another room has a crack coming from the upper corners curving out to the ceiling. My mother-in-law says it is just because the walls are plaster and not drywall. I think it is a support problem in the house. The house is a rental and the landlord is lazy so I really doubt the landlord is taking proper care of the place. If plaster walls were the problem then why are there just a couple cracks upstairs. Water leaks into the basement when it rains and I know I have seen foundation cracks outside. I just lack any expertise to really tell them anything.