I set up wireless networks for many large special events. One event in particular has a large number of private wireless networks that play havoc with our network. It take some creative configuration to keep our network up with all the channels in use.
Though we have never had our wireless network taken down, we have had our wired network taken down by someone plugging a wired router into our network. If both router are on the same IP pool, sometimes the 2nd router will take over the main router. We also had to get creative on our IP pools to avoid this.