They know who you are and where you sleep…….Run…Get Away! j/k
I have seen this a couple of times. Once it turned out to be some HP Printers that came in and hadn’t been configured and they were broadcasting an ad-hoc network looking for a peer. I guess HP was thinking it might help home users to do absolutely nothing but plug it in.
However, the second time I ran into this…it was real perplexing…we saw one Ad-Hoc network named “FreeWifi” or something like that. We went into the basement of our building where we were guaranteed to get zero signal from the outside world. And it still showed up with full signal so we were a bit skeptical and we brought in a Fluke Wireless/Frequency Analyzer and that determined that only a few 20Mhz signals were even making it into that room and there were no signals in the 2Ghz at all. So then we chalked it up to a Microsoft bug. I believe one of my Net Admins found some articles on it. Something about it being a documented bug, I think it was related to Microsoft’s support of the WLAN card.
Hope this helps,
You can find an article detailing an issue like this below