And (sorry for double post) i believe this is the line the debug is talking about:
// SELECT query on database
$this->data = $this->db->query('SELECT ' . $this->db->fieldName('id') . ', ' . $this->db->fieldName('name') . ', ' . $this->db->fieldName('flags') . ', ' . $this->db->fieldName('access') . ', ' . $this->db->fieldName('maxdepotitems') . ', ' . $this->db->fieldName('maxviplist') . ' FROM ' . $this->db->tableName('groups') . ' WHERE ' . $this->db->fieldName('id') . ' = ' . (int) $id)->fetch();
}