A Rogue Network

Hello All,
I am hopeing that somwone might be able to answer a question for me.
I work for a company of aproxametly 200 people. We have an internal wireless network for all of our employees that have laptops.
Lately we have noticed an ad-hoc network in the building. I have done a few scans with miscelaneous software trying to figure out an IP address or a mac address. The Mac address is comstantly changing on the access point that we are connecting to.
The question is… A. How do I figure out whos computer or device the ad-hoc network is set up on.
B. Why the MAC is constantly changing everytime I try to look at it.
C. How big of a security threat this could possibly be.
Thanks in advance