Found the problem, it was me, a noob thing I guess. The "Caspian" scenario is designed for 2v2 play, so I set the first 2 players, myself and an AI, as team 1. i set the remaining 2 AI's as team 2. I didn't realize this setting carries forward onto other maps, including 2-player only maps. The "team 1" settings stayed for the only 2 players, so no opponents, thus an immediate "you won"!!! I reset the two players to team "none" and all works properly now.