Update query is altered by safari???

[eluser]bobbob[/eluser]
I have this odd thing where my update query runs ok in firefox, IE, Camino but in safari it adds a field to the update.
error message is :
Error Number: 1054
Unknown column '_' in 'field list'

There is of course no '_' in my form.
the last part of the error is where it happens:
`ip` = '67.140.22.58', `_` = '' WHERE `id` = '18'

MY query:

Code:

$id = $this->session->userdata('uid');
        $this->db->where('id',$id);
        
        $this->db->update('members',$_POST);

When I rewrite it to:

Code:

$newdata = $_POST['preferred'];
$this->db->query("UPDATE members SET preferred = '$newdata' WHERE id = '$id'");

It runs fine.

What baffles me is that safari appears to change the query.
Any ideas much appreciated.