Edit: guess I misunderstood.
To rebuild an index: REPAIR TABLE tbl_name QUICK;
You'll have to do this for every table with a full-text index that you're searching.
As for adding a * to searches, you'll have to look at vBulletin code to see wherever it's doing its searches. Look for "in boolean mode" or something like that. See
http://dev.mysql.com/doc/refman/5.0/...t-boolean.html for the SQL syntax for MySQL.
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