Meresya

I had one save on a large area city take a long time. I thought it froze as well. I just let it do it's thing and went to bed as I had planned. When I woke up, the game was at the region area. If you stopped the game the first time it appeared to freeze, then this would result in a corrupt file being created, which is what it sounds like has happened (either personnally or computer caused). It doesn't help, but...

The game actually has a base mod of some type. You can see this in action by starting a new region. Name the adjacent city areas you will have as neighborhood connections. Start your new city, and just lay down connections to each of the neighboring cities. Save, then go to each neighboring city and lay the connection road through the area, saving when done. What this means is when you restart your main city, no city has anything but a minor road connection system set up. Most of the sims will travel to one of the neighboring cities in order to work, even though the only thing within those cities is some type of road.