And if you save a backup copy at the same time you will always have a backup game to revert to, because the attempt to save a game without enough memory will result in the file being deleted.
That shouldn't happen with the latest beta, as I changed the way that games were saved so that it saves to a temp file first, then moves the AutoSave to the PreviousAutoSave.
What's really fun is running SH3 and GC2 at the same time.
It's generally not a good idea to run 2 DirectX apps at the same time.
I've had a quite similar problem, but for me it happens after about three or four hours. It doesn't really bother me; I always assumed that it was CPU heat taking its toll on my machine.
Generally it's an out of memory issue; if it crashes while saving, there will be asserts from the memman at the bottom of the debug.err file.
I get the save game crash after about 3-4 hours as well. I play on gigantic maps with about 6 other races.
When the game hits the 2 GB memory mark, Windows cuts off memory allocation for it and won't give it any more. It's not that hard to hit it on a gigantic galaxy with lots of planets and lots of ships. We've been working on trying to reduce the amount of memory that GalCiv2 uses, but it's a fairly big problem and we've run out of easy things to cut down. If you turn down your planet surface variety slider to 0, it will take longer for the out of memory bug to happen in new games.