Just noticed that when I add an icosphere from ADD>MESH I get a sphere that has half its normals pointing the wong way, the following blend illustrates this: (the one on the left has its normals recalculated)
Does anyone have any ideas what is going on? I will reinstall Blender but this is a bit puzzling.
EDIT: just reinstalled Blender 2.57b and the same happens (but not in 2.56a). I may get a newer build.
Shape Glitch.blend (436 KB)