P5S-117, a planet within Ba'al's domain, is one of his principal naquadah mining sites and was selected as the target to test the Avenger virus program. When Avenger seemed to shut down the entire gate network, Felger and Carter traveled to the forested world of ancient stone ruins in order to eliminate the virus, reboot the DHD, and restore the gate system. They accomplished their mission, despite coming under attack by Ba'al's Jaffa, and they were rescued by O'Neill and Teal'c, who arrived in a captured alkesh.
Cross Reference: Avenger, Ba'al
Episode Reference: Avenger 2.0