Petek, thanks for the follow up. Did that. However, after some tedious testing, what I found was, the mod "Really Advanced Setup v1.03.144" was causing the conflict. Unclicking or deleting the mod fixes the problem. I have 50 or so mods that I play with at any one time. I will let the mod author know about this conflict. BTW, I've got a tower (Q9450) and a notebook (I7), both of which Civ 5 ends my game prematurely with this mod active.
Thanks!