Не может быть, что этой таблицы нет, без нее 3.х форум не должен запуститься.
Там что-то типа такого, может подойдет.. Префикс свой поставьте вместо ***
CREATE TABLE `***_rc_classes` (
`com_id` smallint(4) NOT NULL AUTO_INCREMENT,
`onoff` tinyint(1) NOT NULL DEFAULT '0',
`class_title` varchar(255) COLLATE utf8_unicode_ci NOT NULL DEFAULT '',
`class_desc` text COLLATE utf8_unicode_ci NOT NULL,
`author` varchar(255) COLLATE utf8_unicode_ci NOT NULL DEFAULT '',
`author_url` varchar(255) COLLATE utf8_unicode_ci NOT NULL DEFAULT '',
`pversion` varchar(255) COLLATE utf8_unicode_ci NOT NULL DEFAULT '',
`my_class` varchar(100) COLLATE utf8_unicode_ci NOT NULL DEFAULT '',
`group_can_report` text COLLATE utf8_unicode_ci,
`mod_group_perm` text COLLATE utf8_unicode_ci,
`extra_data` text COLLATE utf8_unicode_ci NOT NULL,
`lockd` tinyint(1) NOT NULL DEFAULT '0',
`app` varchar(32) COLLATE utf8_unicode_ci NOT NULL,
PRIMARY KEY (`com_id`),
KEY `onoff` (`onoff`,`mod_group_perm`(255))
) ENGINE=MyISAM AUTO_INCREMENT=23 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci
insert into `***_rc_classes` (`com_id`, `onoff`, `class_title`, `class_desc`, `author`, `author_url`, `pversion`, `my_class`, `group_can_report`, `mod_group_perm`, `extra_data`, `lockd`, `app`) values('2','1','Forum Plugin','This is the plugin used for reporting posts on the forum.','Invision Power Services, Inc','http://invisionpower.com','v1.0','post',',6,13,7,8,3,14,4,9,1,12,11,10,19,20,21,22,23,',',6,8,4,9,11,','a:1:{s:15:\"report_supermod\";i:1;}','1','forums');
insert into `***_rc_classes` (`com_id`, `onoff`, `class_title`, `class_desc`, `author`, `author_url`, `pversion`, `my_class`, `group_can_report`, `mod_group_perm`, `extra_data`, `lockd`, `app`) values('3','1','Private Messages Plugin','This plugin allows private messages to be reported','Invision Power Services, Inc','http://invisionpower.com','v1.0','messages',',4,3,1,6,7,8,9,10,11,12,13,14,19,20,21,22,23,',',4,6,8,9,','a:1:{s:18:\"plugi_messages_add\";s:5:\"4,6,8\";}','1','members');
insert into `***_rc_classes` (`com_id`, `onoff`, `class_title`, `class_desc`, `author`, `author_url`, `pversion`, `my_class`, `group_can_report`, `mod_group_perm`, `extra_data`, `lockd`, `app`) values('4','1','Member Profiles','Allows you to report member profiles','Invision Power Services, Inc','http://invisionpower.com','v1.0','profiles',',4,3,1,6,7,8,9,10,11,12,13,14,19,20,21,22,23,',',4,6,8,9,','N;','1','members');
insert into `***_rc_classes` (`com_id`, `onoff`, `class_title`, `class_desc`, `author`, `author_url`, `pversion`, `my_class`, `group_can_report`, `mod_group_perm`, `extra_data`, `lockd`, `app`) values('5','1','IP.Downloads Plugin','This is the plugin for making reports for the <a href=\'http://www.invisionpower.com/community/downloads/index.html\' target=\'_blank\'>IP.Downloads</a>.','Invision Power Services, Inc','http://invisionpower.com','v1.0','downloads',',1,3,4,6,11,19,13,20,22,23,',',4,6,','a:2:{s:15:\"report_supermod\";i:1;s:13:\"report_bypass\";i:1;}','1','downloads');
insert into `***_rc_classes` (`com_id`, `onoff`, `class_title`, `class_desc`, `author`, `author_url`, `pversion`, `my_class`, `group_can_report`, `mod_group_perm`, `extra_data`, `lockd`, `app`) values('6','1','Blog Plugin','This is the plugin for making reports for the <a href=\'http://www.invisionblog.com/\' target=\'_blank\'>IP.Blog</a>.','Invision Power Services, Inc','http://invisionpower.com','v1.0','blog',',1,3,4,6,11,19,13,20,22,23,',',4,6,','a:1:{s:15:\"report_supermod\";s:1:\"1\";}','0','blog');
insert into `***_rc_classes` (`com_id`, `onoff`, `class_title`, `class_desc`, `author`, `author_url`, `pversion`, `my_class`, `group_can_report`, `mod_group_perm`, `extra_data`, `lockd`, `app`) values('7','1','Gallery Plugin','This is the plugin for making reports for the <a href=\'http://www.invisiongallery.com/\' target=\'_blank\'>IP.Gallery</a>.','Invision Power Services, Inc','http://invisionpower.com','v1.0','gallery',',1,3,4,6,11,19,13,20,22,23,',',4,6,','a:2:{s:15:\"report_supermod\";s:1:\"1\";s:13:\"report_bypass\";s:1:\"1\";}','0','gallery');