   DirectX , C#, ATI card  and invalid triangles
  im new to this forum, so first of all: Hello everyone :)i have a problem writing my university project app. i'm experiencing some strange face behavior, similar to flipped normal effect. it happens on meshes either generated from heightmap in c# (terrain) or  meshes done in blender/3DS, what's more interesting: it doesnt happen on closed-in meshes like guns, boxes, etc., only with plane based terrain.The same code works perfectly on my project-mate's computer with nVidia card ( i have ATI )my card : Radeon HD 3400Driver Packaging Version8.471-080225a1-060442C-DellDirect3D Version   7.14.10.0567I havent experienced this kind of problems in any game i'v played so far.Does anybody know what may be the problem ?   
  Try enabling the debug runtimes, in the DirectX Control Panel.  This will cause the runtime to output debug spew about any errors or warnings.Since you're using C# and you can't see the native debugger spew, you'll want to use DebugView.   