An anonymous reader writes "Almost anywhere you go these days (particularly at airports), if you check for available WiFi settings, you have a pretty good chance of seeing an ad hoc network for 'Free Public WiFi.' Of course, since it's ad hoc (computer to computer) it's not actually access to the internet. So why is this in so many places? Turns out it's due to a bug in Windows XP. Apparently, the way XP works is that if it can't find a 'favorite' WiFi hotspot, it automatically sets up the computer to broadcast itself as an ad hoc network point, using the name of the last connection the computer attempted. So... people see 'Free Public WiFi' and they try to log on. Then their own computer starts broadcasting the same thing, because it can't find a network it knows. And, like a virus, the 'Free Public WiFi' that doesn't work lives on and on and on."