Most likely, the very bottom of the collision sphere of your player is just below the surface of your level mesh.
Try moving the player up (or the level down) a substantial amount just to see if it makes a difference.
something like:
EDIT: Looks like DJW beat me to it.
Try moving the player up (or the level down) a substantial amount just to see if it makes a difference.
something like:
MoveEntity player, 0, 10, 0 or MoveEntity level, 0, -10, 0
EDIT: Looks like DJW beat me to it.