[WPMU DEV Dashboard] Login/php errors

Since at least Dec. 21, we have been experiencing a login redirect loop from wp-login.php which prevents us from logging into the WP dashboard. Whenever any of our admins attempts to login via /wp-login.php/ they are redirected to the following URL http://www.themountleads.org/wp-login.php?redirect_to=http%3A%2F%2Fwww.themountleads.org%2Fwp-admin%2F&reauth=1 . Our php_errorlog is also showing errors for most of the WPMU plugins, showing this error "WordPress database error Can't lock file (errno: 165 - Table is read only)..." followed by references to plug-ins. Your help is appreciated.