Well, okay.
The drivers are fully updated.
I tried playing with the sound hardware acceleration and turning the game sound off.
No change in stability.
So if 3d sound is not a problem for my hardware, my sound card is not the problem.
I guess it's just one of those vague, unclassifiable problems specific to a certain system setup (namely mine). I'm so tired of getting games to work that I'll just pass on this one. A shame, too, because this looked like a really cool, deep game. Anyway, thanks for all your advice; this is one of the most helpful bb's I've encountered.