P5S-117 was a planet in the Milky Way galaxy controlled by Ba'al. In 2003, Stargate Command sent the virus Avenger there which immediately rendered the Dial Home Device useless. Ba'al (or one of his scientists) modified the virus and sent it to every other Stargate in the galaxy, which took out the whole Stargate network. (SG1: "Avenger 2.0")