didn't find on search my problem.
it's discussed here
Aperture stuck in stopped-down position after exposure - Samyang 85mm: Pentax SLR Talk Forum: Digital Photography Review
but, on k-5 it expresses when switching on and off LV and then something stucks. I turn off the camera but k-5 is then confused and nothing works. either I take out the battery or for one degree turn out the lens, then it goes back to normal.
as it's mentioned on dprev forum, seller will replace it.
but maybe there is another solution? maybe it's not exactly the same problem.
I'm really confused, especially when it stucks and k-5 gives out that seizing sound, I don't know how much harm it leaves then.