Are you use PXE for OS deployment by chance? This is usually a record coming up from a machine that is booting up to PXE, which causes the machine to send up a miniscan with this information to the core server. This should be the MAC address of the machine. To try to locate it in the inventory (assuming it's managed) you can build a query to look at the MAC address entry on your devices and see which machine matches up.
i guess it's not showing up in the query results.
this is probably an unmanaged device that is trying to pxe-networkboot. we often have external consultants, etc in our office which try to connect their notebook to our LAN.
just schedule a provisioning task for them ;-)))