It took lots of patches to get to Windows versions of vanilla Civ4 that didn't crash, and video drivers were an ever-present problem in the early days. Version 1.74 is quite a high number! We didn't invent "black ice" on the Mac, it was around on the PC first. There is still a rumoured patch proposed to fix some open issues with BtS. I imagine we are suffering some of those problems, plus new ones created by the need to convert DirectX to OpenGL and OpenAL. There are probably extra issues for PowerPC Macs, with byte order reversal required.