Lol, that one has got me before and it's not as long as it seems New or restarting with something changed? If its something changed then it can take about 90 minutes (iirc) for the network to forget the old one but otherwise it's usually just a few seconds here. Probably someone better to answer along soon though, I tend to take the restart it and swear at it approach and it usually works but no doubt there are better ways of resolving most issues