MySQL Error

SQL query:---- Dumping data for table `mos_content_rating`------ Table structure for table `mos_core_acl_aro`--CREATE TABLE `mos_core_acl_aro` (`aro_id` int( 11 ) NOT NULL AUTO_INCREMENT ,`section_value` varchar( 240 ) NOT NULL default '0',`value` varchar( 240 ) NOT NULL default '',`order_value` int( 11 ) NOT NULL default '0',`name` varchar( 255 ) NOT NULL default '',`hidden` int( 11 ) NOT NULL default '0',PRIMARY KEY ( `aro_id` ) ,UNIQUE KEY `section_value_value_aro` ( `section_value` , `value` ) ,UNIQUE KEY `mos_gacl_section_value_value_aro` ( `section_value` , `value` ) ,KEY `hidden_aro` ( `hidden` ) ,KEY `mos_gacl_hidden_aro` ( `hidden` )) TYPE = MYISAM ;MySQL said: Documentation#1071 - Specified key was too long; max key length is 1000 bytes