Directv customers with HD DVR's can connect their DVR's to their home network. As part of their service, they can download Directv2PC software. When all of this occurs, the servers and renderers will be created on their networked computers.
If you've never had Directv service then someone in your neighborhood is sharing a network connection with you. I would look at my own network and assure that my SSID was a unique identifier so no one could accidentally think it was theirs. I would also check to make sure I wasn't on someone else's network.