I've been shooting with my new (used) Sigma 70-200 HSM for a few days now, and I mounted it this morning on my D70, shot some photos at the Botanical Gardens, and halfway through the day, I got an "EE" error. I checked that it was locked into F32 and that was fine... I mounted my 50mm and it was fine... tried the Sigma again, and got the same error. I tried it on a 2nd D70 with the same problem, so I think I've ruled out the camera. Seems like the CPU contacts aren't working completely. They look fine, and are perfectly clean. I'm going to contact KEH in the morning and see about replacing or refunding the lens. I think it came with a 60 day warranty, and since it's only day 4 or 5 and it stopped working, I hope they'll cover it.