Notice: Use of undefined constant TABLE_PREFIX - assumed 'TABLE_PREFIX' in /usr/www/users/thandt/plog-load_config.php on line 17 Table 'thandt_db1.TABLE_PREFIXconfig' doesn't exist
I assume you have just upgraded to RC1. Have you run the plog-admin/_upgrade.php script yet? Also, it looks like you are signing in the old way through plogger-directory/admin/ instead of the new way plogger-directory/plog-admin/. If you ran the _upgrade.php script, it should have deleted the old files or listed them for you to delete.
If you need more directions on what stays and what goes, I can let you know as well.