Up Arrow creates error in Game

Hi all, I've got a 2D looking sidescroller game that was built in a 3D project. Even though it is a 2D sidescroller game, I am using FPSController. My Horizontal movement keys are the right and left arrows, while the space bar is jump. Everything works just fine when the correct control keys are used (left, right, space). But for some reason when I run the game, if I hold either the up or down arrow, things start to disappear from the game and my character falls through to the endless world.

I thought maybe the up and down arrows were assigned to some sort of deleting function. So I went to InputManager and assigned jump to the up arrow. In game, the up arrow triggers the jump function but it also still makes things disappear.

Any help?