llandewi - I develop under Windows (XAMPP) and have no problems.

You will have problems running older versions of Elgg under PHP 5.3 generally. Nothing to do with my plugin. But if you are running a recent version of Elgg there should be no problems.

Ok, well I'm running elgg 1.7.7. I'll keep looking. If I find something out, I'll post it here. Thanks for the reply!

Well... isn't this interesting! It seems I've found some sort of a solution, although I cannot explain why it works.

At the bottom of form/actions/manage_fields.php, there is the following code:

if ($form_action == 'move') {
    $fields = form_get_fields($form_id);
    echo elgg_view('form/field_list',array('fields' => $fields,'form_id'=>$form_id));
} else if ($redirect_url) {
    forward($redirect_url);
} else {
    page_draw($title,elgg_view_layout("two_column_left_sidebar", '', elgg_view_title($title) . $body));
}

I've changed the 'else' bit to:

} else {
    page_draw($title,elgg_view_layout("two_column_left_sidebar", '', elgg_view_title($title) . $body));
    die();
}

Notice the addition of die(); I don't know why this server needs a die(); to stop redirecting to or loading the homepage one way or another, but at least it works! :)