Rendering problem

Hi there, Im creating a short for a 3d modeling camp,and Im finally done the animations (yay!) so now Im trying to render it. But for some reason, the rendered images go all weird, and the the render window fills only halfway, then and the end of the frame, grows to normal size. Ive never had problems like this before, so I`m relay confused:(
pictures atached


You have ‘Fields’ enabled on the Render panel:-