Search Reloaded failed to create the wp_sem_nodes table. I am running wordpress 1.5.1.3, MySQL 2.0.54, and PHP 5.0.4. After troubleshooting the problem seemed ot be with the FULLTEXT index. The MySQL doc says that FULLTEXT is only available on MyISAM tables. I made the following change to your SearchReloaded init function and the problem was resolved.

$wpdb->get_results("# sem_search_init
CREATE TABLE IF NOT EXISTS `$wpdb->sem_nodes` (
`node_id` int(10) unsigned NOT NULL default '0' ,
`node_name` tinytext NOT NULL ,
`node_content` text NOT NULL ,
PRIMARY KEY (`node_id`) ,
FULLTEXT KEY `node` (`node_name`,`node_content`)
)TYPE=MyISAM
");