Any ideas? Yes. Not an expert by any stretch. If you look inside the camera body at the very top you'll see 8 contacts. You may have at least one that has corrosion or oil, etc. that is preventing contact with the necessary lens information and shows as if you have a non-CPU lens attached. I would try to clean all of these contacts with something like DeoxIT (RadioShack) and then retry the lens. You may also try a total reset of the camera, but I'd try the clean first. Hope it works!