Annoying recentering when scrolling down

[Juanma Barranquero]

I have the following in my .emacs:

(setq scroll-preserve-screen-position 'always
      scroll-conservatively           most-positive-fixnum
      scroll-step                     0)

When moving down with next-line, this used to produce a nice
line-by-line scrolling, with no recentering. That has changed
recently; now I'm getting (very annoying) recentering every now and
then (curiously, this does not happen when scrolling up with
previous-line).

How can I get the old behavior back?

 Juanma