Artifacts in Terrain

I’m encountering the following artifacts in my terrain page on a GeForce FX 5200 in Windows XP.

Those black areas are triangles, and don’t appear under Mac OS X and ATI Radeon X1600.

Does anyone have a clue what might be going on here? Is is faulty drivers, because I’m running the latest NVidia drivers.

I noticed the same thing when I created a simple TerrainPage with a flat height map with "clod" enabled.  I used no textures and just applied a blue material state to the terrain page.  When I disabled clod, the artifacts went away.  I have a GeForce 8800 GT.  I wonder if there could be a bug in the crack-closing algorithm for the continuous level of detail implementation?  In all the terrain examples, clod is always disabled. Although it seems more likely to be an NVIDIA driver bug if it doesn't show up on your ATI Radeon card.