From Halopedia, the Halo wiki
On September 13 to 18, "MB05032" still hijacking Adjutant Reflex communicated with people, prepping them for Halo 3's release by having it countdown to the minute, and having it leave the Adjutant Reflex body as it was too small to contain itself.
The Halo 3 MSN page stated in mid-August that Iris had come to a conclusion with the opening of Server 5. Iris' story and mysteries were continued and addressed in Halo 3, by the use of computer Terminals in the levels taking place on the Ark. These strings of recorded text communications detailed the fall of the Forerunner civilization and the firing of the Halo Rings. It also revealed Adjutant Reflex to actually be a rogue AI called Mendicant Bias, who betrayed the Forerunners in their final hour. In 2009, AdjutantReflex's Bungie.net profile was deleted.