phpbb_search_results       
phpbb_search_wordlist
phpbb_search_wordmatch
şu tabloları sil
# --------------------------------------------------------
#
# Table structure for table `phpbb_search_results`
#
CREATE TABLE phpbb_search_results (
  search_id int(11) UNSIGNED NOT NULL default '0',
  session_id char(32) NOT NULL default '',
  search_time int(11) DEFAULT '0' NOT NULL,
  search_array text NOT NULL,
  PRIMARY KEY  (search_id),
  KEY session_id (session_id)
);


# --------------------------------------------------------
#
# Table structure for table `phpbb_search_wordlist`
#
CREATE TABLE phpbb_search_wordlist (
  word_text varchar(50) binary NOT NULL default '',
  word_id mediumint(8) UNSIGNED NOT NULL auto_increment,
  word_common tinyint(1) unsigned NOT NULL default '0',
  PRIMARY KEY (word_text),
  KEY word_id (word_id)
);

# --------------------------------------------------------
#
# Table structure for table `phpbb_search_wordmatch`
#
CREATE TABLE phpbb_search_wordmatch (
  post_id mediumint(8) UNSIGNED NOT NULL default '0',
  word_id mediumint(8) UNSIGNED NOT NULL default '0',
  title_match tinyint(1) NOT NULL default '0',
  KEY post_id (post_id),
  KEY word_id (word_id)
);
şunları koy hem db küçülür rahatlarsın ve tahminimce sorunda düzelecektir.