I can only see my quad (two indexed triangles) when at least one vertex falls outside of the screen. If the entire quad 'should' be in view, the whole thing disappears. As soon as a vertex hits the screen edge the whole thing reappears. Variations of this: left and right screen edges cause the whole quad to appear/disappear. The top and bottom edges cause only the triangle containing the vertex outside the view to appear but this is likely only due to the order of the vertices. Turning off clipping prevents me from seeing the quad at all. Now, I built this code on an old laptop with a Rage LT Pro (yeah, that old) and I sent the .exe to my friend. He doesn't have this problem at all. I have made quite a few Direct3D apps on this computer prior to this, although none with Managed DirectX so I'm convinced the problem is only partly due to the video card. My device.ClipStatus.ClipIntersection is -1 right after BeginScene() but I don't really know what this means or how to change my clip planes. Does anyone know what might cause this?