Possible bug: In my last game (Gigantic map, masochistic level) I've found a stack of fleets in (almost) every AI's territory. They were not moving and they had mostly obsolete technology. I think the maintance for these ship broke their economy. Probably the Ai cannot upgrade them, but it didn't want to use them...
Other bugs I've found:
-The displayed time for finishing tech/ship/building is NOT correct. It often takes more turn than displayed
-after loading the game, during the first turn no research/producing etc
