I know this is old. But I just got the same problem earlier with my city. I built it myself, I don't have any downloads other than Open Books Library. And my graphics card is an ATI. I don't know what version, I'll have to check. I don't have any patches or fixes and I have Deluxe Edition. What happened was the top half of my city lost LARGE areas of roads, streets, highways. I received the two alerts from the Public Safety Advisor saying there were no roads to my poilice and fire stations. When I rebuilt the whole road system. Everything went well. When I pressed on Turtle Speed my game crashed and closed automatically. Need help please. Matt