Though I know I am posting in wring forum, but the XNA forum is closed, moved away. I tried to access the butty looking forums but even Gamertag didn't help. So please, I am just a coder who does not want to loose his dignity on Xbox pages (and who allready lost half an hour registering for nothing). Here is the problem finally. I dont know since when my application began to render all meshes without z consideration. Not only the meshes are droven over them selfs, but also the back sides of them are droven over them selfes. I think it is an issue with my shaders in fx file I use to render with. The z buffer and projection are set ok and were working correctly. This shader Z problem I am sure someone else have experienced too. the shader is compiled without errors.
Also very interesting is the fact that vertex demands positon in their input to be 4 float vector, wile position in direct3d steam vertex declarations are always 3 float vectors. Why is that (and why ,my shader is so crazy)