One thing that you can do to see if it's a hardware problem is lower the screen resolution and effects. You can do that once you're in a neighborhood, but before you load a lot. Set everything to Low or Off and set your screen resolution to 800x600, then see if you can get into a lot. If it does the exact same thing it has been doing, then I'd want to suspect that there's a problem with your Sims installation. Have you tried reinstalling Sims?
The graphics thing didn't work either. But I'll try reinstalling it.
