D800 autofocus won't engage

My problem seems potentially related, but since it also happened on my D700, it could be a lens issue, rather than a problem with the camera body. In any case, this may relate to one of you or none of you. But, I had some time to kill this morning, so it here goes:

I've also had this happen with Nikon's 70-200, as well as Nikon's 70-300. Basically, the AF will just stop working I get no strange noises or error codes. It's as if the lens is receiving no power. There's no warning, it just happens randomly.

In my case, the problem appears to be isolated to the lenses. It's also happened on my D4 using the same lenses. With that said, I use these lenses very frequently, as of late. I've always resolved the issue by removing the lens and reattaching it. I've examined the contacts on the lens and the bodies and they are spotless.

It could be the AF/M switch. Though, the new AF/M selector switch is quite sturdy and appears to be well insulated from the elements. Then again, so too is the D700 AF-S/AF-C/M Switch. The reason I don't believe it's camera based, in my situation, is that it happened across 3 different bodies. But, for informational purposes it's only happened a single time on my D4, during my first week of ownership and never since that one time.

Therefore in my case, it's a very rare malfunction. If I had estimate it's frequency, I'd estimate it occurs once every 3,000 shots. It sounds like there might be something more serious taking place with those who have responded above. But, I thought I'd add to the knowledge base, as it's generally easier to have a lens properly warrantied than a body, especially as of late with the focus point ssue that Nikon refuses to acknowledge, thus far, or is unable to