Magento基本文件错误

i am facing a big problem in magento. In my magento site user are not receiving the order email. So i enable the Logs and here i found the error.

Error is

 Warning: strlen() expects parameter 1 to be string, array given  in /home/{magento}/public_html/app/code/core/Mage/Catalog/Model/Layer/Filter/Attribute.php on line 93 

and then i went to the attribute.php file and here i found this function

public function apply(Zend_Controller_Request_Abstract $request, $filterBlock)
{
    $filter = $request->getParam($this->_requestVar);
    if (is_array($filter)) {
        return $this;
    }
    $text = $this->_getOptionText($filter);
    if ($filter && strlen($text)) {
        $this->_getResource()->applyFilterToCollection($this, $filter);
        $this->getLayer()->getState()->addFilter($this->_createItem($text, $filter));
        $this->_items = array();
    }
    return $this;
}

i checked that $text is giving me a ARRAY so that this problem is coming but this is a base file and i haven't change anything in this so how this error have been occurred.

Please help...