That is not an appropriate error. The error states table user_messageboard does not exist and the query in your error is not referencing it. Clearly the error and the query have nothing to do. Please, provide the appropriate error and query.
Having said that, clearly, some query is using user_messageboard which just doesn't exist. Probably a plugin is using that table but I don't know of any which does... and even if it is a plugin then the plugin developer should correct the table name as it is not using the "qa" prefix