Still getting crashes after 1.11

I'm well into a huge universe sized game, which was going well until recently when the game crashes every few turns. Lately this seems to happen most often right when another civilization discovers a precursor ship. I get the notification screen, then 'boom' game shuts down. When I go back to the previous save it takes a very long time to load...like 3-5 minutes. Here are my system specs:

Dell Dimension 4600i
Pent IV, 2.8 Ghz
Memory 510 MB
Radon 9600 driver

Don't know what else you need. I really love this game but playing is becoming an exercise in futility.