Scandinavian characters not showing in order comments in admin

Hi,

We've recently updated PHP on our webserver to Version 5.4.27. We experienced problems using Scandinavia characters in product description fields but solved it by using :

htmlspecialchars(stripslashes($products_name[$languages[$i]['id']]), ENT_COMPAT,'ISO-8859-1', true));

in /httpdocs/admin/includes/modules/product/preview_info.php

...

In admin when I know try do update an order with customer information which includes special characters. The comment field is blank when updated. The data is saved to the database with correct characters and sent OK to customer..

So I probably need to update another PHP-file with the compability info shown above, but I need help top locate which file does the update..

Thanks in advance, :D