WP won’t recognize known users in its database

(I’m using 2.8.5, though the selector for this post doesn’t list that as an option.)

My local development copy of wordpress no longer recognizes known users in its database. Wp-login returns “Invalid Username” for all users.

This is what I have checked.

wp-config: database name, mysql username, mysql pass, dbase location, dbtable prefix’s are correct.

phpmyadmin: all appropriate tables exist with user and post information. No overhead in any table, though I ran repairs anyway.

wp-login: tried a fresh copy of wp-login. No change in result.

For me the user and post information isn’t important, for this is a development copy. What I am trying to preserve is my configuration.

Is there anything else I can check?

Thanks a lot everybody.