For what it's worth, I started a new game, and I haven't had the disappearing walls bug again.
Also, to clarify, it's not that the game crashes when I set it to a low resolution-- rather, it tries to adjust the resolution on its own for some reason, and crashes at the same time. I wouldn't have even known about the resolution change if my monitor didn't have a box that appears whenever the resolution changes. (And if it weren't the fact that the resolution change persists when I start the game back up.)