Discuz! System Error 您当前的访问请求当中含有非法字符，已经被系统拒绝错误解决

Discuz! X3.1 正式版含目前最新版[2014-03-01]在用户退出时偶尔会提示如下错误，特别是数据整合后的站点：
错误代码：

    Discuz! System Error
    您当前的访问请求当中含有非法字符，已经被系统拒绝
    PHP Debug
    [Line: 0022]search.php(discuz_application->init)
    [Line: 0071]source\class\discuz\discuz_application.php(discuz_application->_init_misc)
    [Line: 0552]source\class\discuz\discuz_application.php(discuz_application->_xss_check)
    [Line: 0355]source\class\discuz\discuz_application.php(system_error)
    [Line: 0017]source\function\function_core.php(discuz_error::system_error)
    [Line: 0024]source\class\discuz\discuz_error.php(discuz_error::debug_backtrace)

临时解决方法：
修改 \source\class\discuz下的discuz_application.php文件大约第350行的private function _xss_check()方法：

    private function _xss_check() {  
      
    static $check = array('"', '>', '<', '\'', '(', ')', 'CONTENT-TRANSFER-ENCODING');  
      
    if(isset($_GET['formhash']) && $_GET['formhash'] !== formhash()) {  
    system_error('request_tainting');  
    }  
      
    if($_SERVER['REQUEST_METHOD'] == 'GET' ) {  
    $temp = $_SERVER['REQUEST_URI'];  
    } elseif(emptyempty ($_GET['formhash'])) {  
    $temp = $_SERVER['REQUEST_URI'].file_get_contents('php://input');  
    } else {  
    $temp = '';  
    }  
      
    if(!emptyempty($temp)) {  
    $temp = strtoupper(urldecode(urldecode($temp)));  
    foreach ($check as $str) {  
    if(strpos($temp, $str) !== false) {  
    system_error('request_tainting');  
    }  
    }  
    }  
      
    return true;  
    } 

替换为

    private function _xss_check() {  
    $temp = strtoupper(urldecode(urldecode($_SERVER['REQUEST_URI'])));  
    if(strpos($temp, '<') !== false || strpos($temp, '"') !== false || strpos($temp, 'CONTENT-TRANSFER-ENCODING') !== false) {  
    system_error('request_tainting');  
    }  
    return true;  
    }