texture problem

I had a texture problem that would like to ask for help. After I applied a texture and applied lighting to all faces, and also set all to double face, some faces appears to be black. It’s just like the lighting affected only the back of the textured face and not the top face. when the light is on the top face, the back is affected instead, while the top face remains black, and vice versa…Is this blender bug or is there a way to solve it? thanks in advance =)

Maybe you have set the reflection to maximum (shading -> material buttons -> shaders)? Did you make some changes with the light?
Screenshot of the material properties or blend file would help…

here’s an example -> http://www.box.net/shared/im657uyqgh
for some reason, when I toggle between edit and object modes the problem is temporarily solved. But when I closed the program and open again, the same problems was still there… the problem didn’t solve in any way…

Try re-calculate normals outside CTRL+N

nope…problem was still there after it’s saved and reopen it…

You might have to do it one face at a time. I have no idea why, but that has happened to me before. Select one wrong face, hit ctrl-n, and if that doesn’t do it you might have to go ctrl-shift-n. You can turn off two-sided after that. Sometimes when you bevel or something and the cut crosses itself, faces get turned inside out, making the computer calculate light on the wrong side. I don’t know if it’s a bug or what, but if that is the case, doing ctrl-shift-n one face at a time should do it.

thanks! the problem is solved and that has been a great help =)