Holes in the ground

Hello,

My team and I have written a game using Torque.
The terrain in the game is completely flat.
The players sometimes fall through the floor for no reason.
Right now we solve it by checking if the player is below the
floor and respawning them if they are. That, however, is
a pretty lame way to fix this.
Is there some reason that the ground collision would suddenly fail?
Is this a bug in Torque or is there some way we could have caused
this while building the level?

Thanks