Right, couple of starters.
First you can post the name of the website without the www and the .com or .co.uk, google can do the rest.
Do you have portal set in the options as standalone, front page, or integration?
Second, you can have a look in the following file (assuming you have ftp access)..
Sources/subs.php
find where it says
// All the buttons we can possible want and then some, try pulling the final list of buttons from cache first.
and below you should see the array for the buttons on the menu bar, something like this.
$buttons = array(
'home' => array(
'title' => $txt['home'],
'href' => $scripturl,
'show' => true,
'sub_buttons' => array(
),
'is_last' => $context['right_to_left']
),
'forum' => array(
'title' => 'Forum',
'href' => $scripturl . '?action=forum',
'show' => true,
'sub_buttons' => array(
),
),
if it looks something like that , then theres no reason it should open in new window and its a forum settings somewhere.
my portal is set as FRONT PAGE.. I think standalone might cause it to see the forum as an external site and open in new window,