On March 20 2012 a Ural AL Airbus A320 failed to taxi as instructed after vacating the landing runway 12L at Dubai and crossed the lit stop bar of an intersection access to runway 12R before stopping just in time to prevent a collision with a Boeing 777 about to pass the intersection at very high speed on take off. Taxi clearance had been correctly given and acknowledged. The aircraft commander had extensive aircraft type experience but the inexperienced First Officer appeared to be undergoing early stage line training with a Safety Pilot present. The Investigation is continuing.