Problem Deleting members


every time I try and delete a member I get this message:
Server Error
Mysqli statement execute error : Cannot delete or update a parent row: a foreign key constraint fails (`savage_xen`.`lpsf_response`, CONSTRAINT `lpsf_response_ibfk_2` FOREIGN KEY (`user_id`) REFERENCES `xf_user` (`user_id`))
  1. Zend_Db_Statement_Mysqli->_execute() in Zend/Db/Statement.php at line 297
  2. Zend_Db_Statement->execute() in Zend/Db/Adapter/Abstract.php at line 479
  3. Zend_Db_Adapter_Abstract->query() in Zend/Db/Adapter/Abstract.php at line 661
  4. Zend_Db_Adapter_Abstract->delete() in XenForo/DataWriter.php at line 1784
  5. XenForo_DataWriter->_delete() in XenForo/DataWriter.php at line 1737
  6. XenForo_DataWriter->delete() in XenForo/Controller.php at line 916
  7. XenForo_Controller->_deleteData() in XenForo/ControllerAdmin/User.php at line 574
  8. XenForo_ControllerAdmin_User->actionDelete() in XenForo/FrontController.php at line 310
  9. XenForo_FrontController->dispatch() in XenForo/FrontController.php at line 132
  10. XenForo_FrontController->run() in /home/savage/public_html/community/admin.php at line 13
Any help would be greatly appreciated.

Thank You