[Victor D]

you likely need to prevent pages.php from raising error if no page content found
replace

PHP Code:

if (isset($HTTP_GET_VARS["pageid"])) {
#
# Prepare data for editing
#
    $preview = ($mode=="preview" ? "" : "AND active='Y'");
    $page_data = func_query_first("SELECT * FROM $sql_tbl[pages] WHERE pageid='$pageid' $preview AND level='E'");

    if ($page_data["language"] != $store_language) {
        $page_data = func_query_first("SELECT * FROM $sql_tbl[pages] WHERE filename='$page_data[filename]' $preview AND level='E' AND language='$store_language'");
    }

    if ($page_data) {
        $filename = $pages_dir.$page_data["filename"];
        $page_content = func_file_get($filename, true);
        if ($page_content === false) {
            $page_content = func_get_langvar_by_name("lbl_page_not_found", array(), false, true);
        }
        $smarty->assign("page_data", $page_data);
        $smarty->assign("page_content", $page_content);

        $location[] = array($page_data["title"], "");
    }
    else {
        func_header_location("error_message.php?page_not_found");
    }

    $smarty->assign("main", "pages");
} 


with

PHP Code:

if (isset($HTTP_GET_VARS["pageid"])) {
#
# Prepare data for editing
#
    $preview = ($mode=="preview" ? "" : "AND active='Y'");
    $page_data = func_query_first("SELECT * FROM $sql_tbl[pages] WHERE pageid='$pageid' $preview AND level='E'");

    if ($page_data["language"] != $store_language) {
        $page_data = func_query_first("SELECT * FROM $sql_tbl[pages] WHERE filename='$page_data[filename]' $preview AND level='E' AND language='$store_language'");
    }

    if ($page_data) {
        $filename = $pages_dir.$page_data["filename"];
        $page_content = func_file_get($filename, true);
        if ($page_content === false) {
            $page_content = func_get_langvar_by_name("lbl_page_not_found", array(), false, true);
        }
        $smarty->assign("page_data", $page_data);
        $smarty->assign("page_content", $page_content);

        $location[] = array($page_data["title"], "");
    }
    else {
        func_header_location("error_message.php?page_not_found");
    }

    $smarty->assign("main", "pages");
}  else {
    $smarty->assign("main", "pages");
}