Mal

If the problems are the hinges, and this is usually the problem with doors, the fix is cheap. Pound toothpicks or chopsticks (latter is better) in the screw holes. Then, re-screw in the hinges to the wall. The hard part is putting the door back up, which you need a buddy to help. The real cost is for beer and pizza to say thank you for the help.

If it's all the doors in a whole section though it's probably something to do with the foundation being out of level.

After taking a look, I'm thinking it might be the roof... nobody lives in the converted garage so it should be find even if it comes down... On a side note, when I first moved in, another door in the house was a little off but it fixed itself.