Got "Disallowed Key Characters." with semicolon on URL

Hi,

I got this error that is “Disallowed Key Characters.” and with a semi colon ; on the URL when redirecting to some page.

I just passing a encoded value to redirect like

.com/index.php/redirect/?orpnt=http://nova.com/ar/index.php/forums/?forum_id=17&topic;_id=

Then in my login form I used

<?php 
if(isset($_REQUEST['orpnt'])){
$orpnt = urldecode($_REQUEST['orpnt']);
}

?>

followed by I set this value in hidden variable like <input type=”hidden” name=”go” value=”<?php echo $orpnt ?>”>

Actually the $_REQUEST method is working correctly but after successfully logged in finally the redirection page having a “;” on the URL and got the error that is the disallowd char.

Please how can I remove that ‘:’ from the URL?