I've searched, and found no discussion of this. Writing posts, I invariably end up with a line or two in the middle where every normal space is replaced with HTML non-breaking spaces ( ). This is making the line in question extend well beyond the borders of the post area when viewing. I was getting this behavior with a totally standard WP install, and when I tried to use the HTML editor there, it always trashed my post contents. I installed the editMonkey plugin, and while the HTML editor now works, the non-breaking spaces still happen.
Using WP 2.0.3, server has PHP Version 4.4.1, computer is Windows XP pro (up to date), and Opera 9.01 (suggestions to switch to different browsers will be ignored).