<p>I had the same problem a couple of years ago. Sent it to Nikon Pro, got it back with a brand new AF motor. Seemed OK. It's a backup so it ended up in the closet for several months. Took it out to do some shooting one day and it would barely move intermittently. After a while it completely quit.<br>
So I don't know if Nikon lied to me about the new AF motor and stole $350 from me, or there's some other problem that causes this. It's frustrating to pay somebody a lot of money for nothing in return.</p>