Re-enable your phpbb_search_wordlist and phpbb_search_wordmatch tables
Your phpBB phpbb_search_wordlist and phpbb_search_wordmatch tables may be converted to the Blackhole Database Engine, rendering the search feature of your forum incapable of returning results. This is done in automation on our servers when these tables exceed 300 MB in size to protect our MySQL servers and maintain reliable service for others.
By default, the search feature of this application grows increasingly inefficient as the size of the forum grows. Extremely large tables are usually an indication of a forum which has been overrun with Spam.
You may contact customer support and demonstrate that your phpBB site is not overrun with Spam and that you have a legitimate case for these tables in excess of 300 MB. In this case, we will mark your database as "Do Not Blackhole", re-enable the tables, and re-index the posts of your site for you.