Unsecured computer-to-computer network on my wireless

Recently I found a “Unsecured computer-to-computer network” showing up on my wireless network on my laptop in a Choose a wireless network dialog box. It displays a Manual connection with one signal strength bar. Obviously I am not going to connect to it specially when I don’t know which laptop it hooked to.
I know I did not install it. How can I remove / delete this connection?
I have a Siemens Gigaset SE567 Wireless ADSL Gateway.
Thanks.