I'm sorry to have posted so often lately about this boring topic. I'm doing so in an effort to say thanks to those who helped me, to help others who might have similar problems, and to keep a record of what I did in case I have to do it again! Hopefully this will be the last of the WP update posts...
This problem was completely behind the scenes, but annoying none-the-less. From the administration section of my blog, I've been unable to view anything past page 1 of an extended list. Categories, Comments, Posts – whatever. The screen shows "1, 2, 3...8 next", but mousing over any of the numbers brings up a link for "http:///?paged=2", without the proper URL.
The fix is to edit the wp-settings.php file by replacing every instance of PATH_INFO with ORIG_PATH_INFO. At least, that seems to have fixed the problem, and I haven't noticed anything else broken (yet.)
Thanks to Squonk23 on the WordPress support forum for blazing this trail for me. More details here (http://wordpress.org/support/topic/193193?replies=2) and here (http://trac.wordpress.org/ticket/7058).
update 8/7/08: the fix described above worked for the backend, but broke ALL permalinks on the site. Today I replaced the original wp-settings.php file (so the site actually works), and I'll continue to search for a cure...
Your past the point of frustration Realtor,