I've tried formatting CF card in the camera and on the computer as well. It didn't help.
Whats more, I've tried downloading and installing the firmware again. It's the newest that is possible for my body - D300 (without S) It didn't work.
My problem appeared after takeing 4 thousand pictures, the body has only 15, so it's fresh The body didn't fall down or sth.
One thing is strange, after takeing few pictures I can review them, separetly, maximise and so on. Just like it was before, when body worked properly. But when I turn the camera off and on the problem appears.