P5S-117 was a planet in the Milky Way galaxy controlled by Ba'al.
History
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. However, Earth's Stargate was still working, since it did not use a DHD. This allowed Felger and Carter to travel to P5S-117 in hopes of fixing the problem. Felger modified his anti-virus and neutralized the new version of Avenger, adding a system patch so this virus could not be used again. (SG1: "Avenger 2.0")