Same problem. Random mode settings and lens focus "hunting" accompanied by beeps at each random setting. In my opinion the camera had a latent defect either in design or manufacture and only a matter of time before it showed up. Working with Nikon Support resulted in them suggesting I send the camera for "repair." I've read more than a few reports that the repairs do not fix the problem.
Nikon does not seem to know about it, acknowledge it, or is purposely ignoring it. By sending it to repair facility, Nikon washes its hands of the problem and makes it an issue between the camera owner and the repair facility.
It seems a shame that a company with a good reputation should take this approach. As for me, I'm going to write it off as a total loss - maybe sell it for parts on E-bay. Remember the adage: "Fool me once, shame on you, fool me twice, shame on me.
First and last Nikon for me.