Problem with Rendering. Square patches of missing light

I’ve been following a tutorial, and everything seemed to be going fine. Then i hit this problem while rendering. I have no idea how to fix this…

The image is the final render result saved out.

These patches will not go. If i move the light source around (a single Sun lamp), the square patch moves around too. Same with if i move the camera. If i turn blender off and on again, the patch also changes position.

Is there anything i can do to fix this?

I’m using Blender 2.62, and this is the standard default renderer.

Thank you for reading

Attachments


I have just noticed that the darker patch lines up with the tiles during the render process. I hope that this makes the problem clearer. Is there anything that i could have done to cause this?

Surface normals facing the wrong way?

No, it’s not that, The normals are all facing the correct way. Also, the patch keeps changing places every time i render…