In two different TA beta i've had an AI build so many ships that there starport becomes full and then fail to move ships from a planet so they can no longer build new ships.

First time it was the Korath, they filled there planets completely with spore ships.

In my latest TAB3b game the terrans have filled there 6 planets with 60 miners. (Side point: they only have 3 asteroids). It's 5 years into the game and there starports have been full for 3 years plus I believe.