What sensor are you using? What is the subject? What is the ambient lighting like? Are you sure the focus shift is not due to 1) your body movement, 2) camera movement, or 3) subject movement? Are you sure it is not due to shallow DOF?
say i was taking picture of a hand, it seems to calculate the closing distant incorrectly and focus to the background... so the background is sharp, but the hand is all blurry... maybe is the lack of ambient light... I just wonder will the D70s do better?