If I happen to alt-tab out of the game (or some uppity program decides to switch out), most of the time the game crashes with a "the program has encountered a problem and needs to close" message from Windows. This doesn't happen exactly all the time. On a rare occasion the game continues running without problem, but I haven't noticed any pattern for when this happens.

Here's my system specifications:

AMD Athlon 64 3500+
2 GB RAM
nVidia GeForce 8600 GT
Sound Blaster Live! 5.1
Windows XP Service Pack 3

I hope there is a solution to my problem other than "just use the mid-game save function".