Horrible Problems With Interior Collision

Sometimes the interiors that I make in Torque Constructor work perfectly, but sometimes the collision is ridiculously off. For example, here's an interior I made that the player completely passes through except for one wall, and only from one side:

http://projectenthalpy.com/fortheloveofgodhelp.dif

Any idea what's going on? Is it a bug? Something I'm doing wrong? Is there a way to fix it while still having the building look the same?