I think this may be related to the NVIDIA problems civ 4 seems to have had a lot of. I experienced some crashing on my previous laptop, which had an ATI chipset of some sorts. On my new laptop (Dell M1330 running vista, NVIDIA M840 GS graphics), suddendly Civ4 BTS just goes to black. Sound shuts off, and I can do nothing except force-shutdown my computer. Obviously this is pretty infuriating. I don't know if this is specific to BTS, as I havn't tried Civ4 on this computer without it. Will try this now, but does anyone know anything about this bug?