So I had this problem with strange wifi's showing up around the building. ad hoc networks at that. free public wifi... Rovernet... linksys... Where on earth are these things coming from. Well so a coworker got his hands on a program that would tell you the strength of wifi networks. So we set off wandering the building to find these things. And we did. Way back in the sales pit, we had signals as big as a house. So the sales people were out at a sales promotion and we started shutting down computers. We found the computers that were creating these things and the mac addresses that were being shown by these things did not match the machines mac address by our network inventory system.
This had me thinking that this was some sort of Trojan that our Trend Micro was not picking up. But a quick google search later and I discovered this site. Which states that it is a bug in Microsoft's Wireless Zero Configuration. Basically they stated that once you connect to an ad hoc network (maybe at an airport or some other public place.) Your computer will try to connect to it the next time you boot up. And if it doesn't find it then it will make your laptop that ad hoc network.
So how do I fix this across a number of computers and not have to log in to each one to disable this ability? Thankfully Microsoft Technet came through for me and told me how to do it in a 2003 AD. So I followed the instructions on the site and created a GPO that disabled the ability to connect to an ad hoc network wirelessly.
Then it was time for lunch. After lunch the coworker and I found that all ad hoc networks were gone. But the users were still using those laptops that we found the networks were coming from before.