If M-x align deletes a lot of whitespace doing its alignment it can get
an "Invalid search bound" error.  Eg. with foo.el below

    emacs -Q foo.el
    M-x end-of-buffer
    M-x align
    => Invalid search bound (wrong side of point)

In `align-region' it seems `last-point' is established from `b' which is
an integer buffer position but that position is invalidated by
whitespace deletes before that point (done by `align-regions').

I get some joy from making the marker before changing the buffer, per
below.  Alternately (untested!) perhaps `b' could be a marker to start
with, ready to be the new value of `last-point'.

2010-05-17  Kevin Ryde  <user42@zip.com.au>

	* align.el (align-region): For `last-point' take marker of b
	position before align-regions because that function inserts or
	deletes text before there.  In particular fixes "Invalid search
	bound" when there's two sections in the region and alignment in
	the first deletes a lot of whitespace.