form_validation have any prolem when client'os is Win7 64bit !

[eluser]Unknown[/eluser]
I’m having kind of an issue here, form_validation have any prolem .
From login form, client post email and password to server. If client's os is WinXP, Linux, Win 7 86 . . . my website work very well.But if I user Win 7 64bit for client' OS, $this->form_validation->run() always return false.

I try to debug run() funtion in form_validation class, print all data in $row to browser :

Code:

foreach ($this->_field_data as $field => $row)
  {
   var_dump($row); echo "<BR>";
   if ($row['is_array'] == TRUE)
   {
    $this->_field_data[$field]['postdata'] = $this->_reduce_array($_POST, $row['keys']);
   }
   else
   {
    if (isset($_POST[$field]) AND $_POST[$field] != "")
    {
     $this->_field_data[$field]['postdata'] = $_POST[$field];
    }
   }

   $this->_execute($row, explode('|', $row['rules']), $this->_field_data[$field]['postdata']);
  }

result is :

Code:

array(7) { ["field"]=> string(5) "email" ["label"]=> string(8) "Email Id" ["rules"]=> string(20) "required|valid_email" ["is_array"]=> bool(false) ["keys"]=> array(0) { } ["postdata"]=> NULL ["error"]=> string(0) "" }

array(7) { ["field"]=> string(22) "change_location_select" ["label"]=> string(4) "City" ["rules"]=> string(8) "required" ["is_array"]=> bool(false) ["keys"]=> array(0) { } ["postdata"]=> NULL ["error"]=> string(0) "" }

the problem is :["is_array"]=> bool(false) ???

How to fix this issues, please help me. Thanks