Collision with scaled interiors / difs

I've never done that, but there seem to be folks who scale interiors (DIFs) in-engine/in the mission editor... this seems to screw a lot of things up, e.g. the object box isn't scaled with them and therefore (?) collision doesn't work as expected etc. - and, more important to me, the navgraph generation for our AI stuff isn't working for scaled interiors either... here is how the navmesh would look for them:


We are using the objBox of the interiors to place all nodes in object space, and as you can see, the box isnt scaled with the interior... :/

Box3F box = interiors[i]->getObjBox();

Now, I figured I could just scale the box accordingly, and I took some code from worldEditor.cc (and the help of Paul Dana - thanks dude! :)) to do this... it basically looks like this:

Box3F objBox = interiors[i]->getObjBox();
      MatrixF mat = interiors[i]->getTransform();
      VectorF scale = interiors[i]->getScale();

      Point3F projPnts[8];
      for(U32 j = 0; j < 8; j++)
      {  
         Point3F pnt;
         pnt.set(BoxPnts[j].x ? objBox.max.x : objBox.min.x, 
               BoxPnts[j].y ? objBox.max.y : objBox.min.y,
               BoxPnts[j].z ? objBox.max.z : objBox.min.z);
         // scale the point
         pnt.convolve(scale);
         projPnts[j] = pnt;
      }
      // now find min and max values for our new Box3F
      Point3F min,max;
      min = projPnts[0];
      max = projPnts[0];
      
      for (U32 k=0; k<8; k++)
      {
         if (projPnts[k].x < min.x)
            min.x = projPnts[k].x;
         if (projPnts[k].x > max.x)
            max.x = projPnts[k].x;
         if (projPnts[k].y < min.y)
            min.y = projPnts[k].y;
         if (projPnts[k].y > max.y)
            max.y = projPnts[k].y;
         if (projPnts[k].z < min.z)
            min.z = projPnts[k].z;
         if (projPnts[k].z > max.z)
            max.z = projPnts[k].z;
      }
      
      // ok, this should hold the scaled objBox now:
      Box3F box(min, max);

So far, so good... but unfortunately, this crashes the engine... I've printed out the box values and they all look good, but for some reason it just crashes while doing raycasts inside the interior to generate the Nodes...
the final crash is at interior.h, 683:

inline bool Interior::isBSPLeafIndex(U16 index) const

called from interiorCollision.cc, line 289:

bool Interior::castRay_r(const U16      node,
                         const U16      planeIndex,
                         const Point3F& s,
                         const Point3F& e,
                         RayInfo*       info)

the RayInfo passed in here seems to be invalid... so I guess there really are some serious collision problems with scaled interiors... does anybody have any insights on scaling interiors and collision?