Ficky interiors? (Crash when relighting scene)

I'm having issues with getting some interiors I've made to work with Torque. They cause the engine to crash when it's in the relighting phase (and is calculating shadowvolumes). In particular, here's a sample of the traceback:

ShadowVolumeBSP::createPoly() line 281 + 3 bytes
ShadowVolumeBSP::splitPoly(ShadowVolumeBSP::SVPoly * 0x0192c848, const PlaneF & {...}, ShadowVolumeBSP::SVPoly * * 0x0012f2c8, ShadowVolumeBSP::SVPoly * * 0x0012f2c4) line 85 + 8 bytes
ShadowVolumeBSP::insertPoly(ShadowVolumeBSP::SVNode * * 0x01928634, ShadowVolumeBSP::SVPoly * 0x0192c848) line 198
ShadowVolumeBSP::insertPolyBack(ShadowVolumeBSP::SVNode * * 0x01928454, ShadowVolumeBSP::SVPoly * 0x0192c848) line 240
ShadowVolumeBSP::insertPoly(ShadowVolumeBSP::SVNode * * 0x01928454, ShadowVolumeBSP::SVPoly * 0x0192c848) line 190
ShadowVolumeBSP::insertPolyBack(ShadowVolumeBSP::SVNode * * 0x019280e4, ShadowVolumeBSP::SVPoly * 0x0192c848) line 240
ShadowVolumeBSP::insertPoly(ShadowVolumeBSP::SVNode * * 0x019280e4, ShadowVolumeBSP::SVPoly * 0x0192c848) line 190
ShadowVolumeBSP::insertPolyBack(ShadowVolumeBSP::SVNode * * 0x01927eb4, ShadowVolumeBSP::SVPoly * 0x0192c848) line 240
ShadowVolumeBSP::insertPoly(ShadowVolumeBSP::SVNode * * 0x01927eb4, ShadowVolumeBSP::SVPoly * 0x0192be70) line 206
ShadowVolumeBSP::insertPolyBack(ShadowVolumeBSP::SVNode * * 0x0012fac8, ShadowVolumeBSP::SVPoly * 0x0192be70) line 240
ShadowVolumeBSP::insertPoly(ShadowVolumeBSP::SVNode * * 0x0012fac8, ShadowVolumeBSP::SVPoly * 0x0192be70) line 190
ShadowVolumeBSP::insertPoly(ShadowVolumeBSP::SVPoly * 0x0192be70) line 130 + 48 bytes
SceneLighting::addInterior(ShadowVolumeBSP * 0x0012faac, SceneLighting::InteriorProxy & {...}, LightInfo * 0x015b5ccc, int 0) line 882
SceneLighting::InteriorProxy::light(LightInfo * 0x015b5ccc) line 322
SceneLighting::processEvent(unsigned int 0, int 0) line 1181 + 51 bytes
SceneLightingProcessEvent::process(SimObject * 0x0191d460) line 120

mPolyStore seems to be thoroughly trashed. (Contains 0xcccccccc) This only happens when I insert a particular set of geometry in my interior. (It's a railing on the edge of a walkway.) If I delete it, things work fine. Map2dif says this:

** Executing...
** Command: D:\TORQUE~1\torque\tools\map2dif.exe
** Parameters: "d:\torquehead\torque\grm\robotmonster\data\interiors\city\dock.map"

Successfully opened map file: d:\torquehead\torque\grm\robotmonster\data\interiors\city\dock.map
  Parsing mapfile...done.
  Creating BSP...done.
  Marking active zones...done
  Creating surfaces...done.
  Lightmaps: Normal...Alarm...done.
  Resorting and Packing LightMaps...done.

  STATISTICS
   - Total brushes:      50
     + structural:       50
     + detail:           0
     + portal:           0
   - Number of zones:    1
   - Number of surfaces: 486

  ** ***  WARNING WARNING WARNING  *** **
  *** **  WARNING WARNING WARNING  ** ***

   Errors exists in this interior.  Please use the debug rendering modes
    to find and correct the following problems:

   * Ambiguous brushes: 0
   * Orphaned Polygons: 6

  *** **  WARNING WARNING WARNING  ** ***
  ** ***  WARNING WARNING WARNING  *** **

  Exporting to runtime...done.

 Writing Resource: persist..(d:/torquehead/torque/grm/robotmonster/data/interiors/city/dock.dif) Done.

Anyone have any clue? I'm digging through the code now to see if I can find what might be going on. The interior code isn't liking something, but I can't grasp what.