I have a Joomla 2.5.14 installation. Registered users are not able to log in to the front-end on the site. Administrator/super users have no problem logging in.
I have tried the suggestions at http://docs.joomla.org/Fixing_the_assets_table
, but those symptoms were not exhibited on this system, and the procedures do not appear to have worked.
I have looked in the PHP logs (/logs/error_log.php and another error_log.php above the document root), and found nothing of interest.