Originally posted by koguma I think that's what may have happened to me. I'm not sure what the aperture was at the time, just noticed that the number was red, and the ISO was 6400 (and red). I could still see a bit, but not enough for it to focus or take a pic. Really weird that it happened three times in a row. Something in that scene (baby pic) it didn't like. I wonder if this is a firmware bug.
A friend of mine, otherwise not into photography, went out and bought a new DSLR and a few rather expensive primes last year. As I got to help/advice in the choice, I asked what the occasion was that he wanted to photograph, if he and his wife were off on vacation or something - nope, he replied (and I quote from his email): "we plan on having a baby in 2014, and I really do not want to inflict any more bad baby-shots on the world....there's a limit to how many out-of-focus, ill composed, with a color-cast, snapshots of puffy, wrinkled, pink, off-spring the world needs, now, isn't there....so I figure if I start practicing now....."
So I am guessing that the engineers at Pentax are trying to do humanity a favor here, by preventing certain photos from being taken, and that you simply was collateral damage from an overly simple algorithm {if (baby-in-frame) then {lock-up} } not factoring in the skills of the photographer.... ?
On a more serious note, I have not experienced that which you say here at all, so I am of no help I'm 'fraid.