Maybe the table does exist already? When you try to initialize the engine and something goes wrong it is probably after the table creation. If you then correct openfts related problems you will still get this error, as the table is already in the db. The initialization code is not very smart.
Openfts easily gets in a status were it is not correctly installed but you cannot remove it. Drop every openfts related table in the db and restart the initialization.
drop table YOUR_INDEX_TABLE; ( txt or fts_fulltext_index )
drop table fts_unknown_lexem;
drop table fts_conf;
-- drop index tables
drop table index[1-10];
