We need to turn off D3D clipping and I call SetRenderState(D3DRS_CLIPPING, False). It works fine on all video cards excluding one PC with Geforce 8600GT under WinXP SP2, DX9c, ForceWare 169.21. D3D incorrectly renders quads when I render to rendertarget. The problem looks as somebody shift X,Y coordinates of triangles. Same PC loaded under Vista works fine. Even more, I installed this video card to other two PCs with WinXP and exactly same Geforce 8600 worked fine (same ForceWare, WinXP SP2, DX9c). If I don NOT calll SetRenderState(D3DRS_CLIPPING, False) all works fine on this strange PC. We develop multimedia application with 2D other 3D and sometimes we need to place objects in 3D and set Z<0 for some triangles. In the test where problem occurs all triangles were placed at Z=0 and in orthogonal projection. - We don't use Z buffer. - No warnings in debug mode of DirectX.

I just found that if add SetTransform after before every rendering to rendertarget solves the problem.