Also if you do a SHOW INNODB STATUS you get this relevant portion..
Code:
LATEST FOREIGN KEY ERROR\n------------------------\n130301 10:49:53 Error in foreign key constraint of table peq/merc_inventory:\n FOREIGN KEY (merc_subtype_id) REFERENCES merc_subtypes (merc_subtype_id)):\nCannot resolve table name close to:\n (merc_subtype_id))\n------------\n