1. The crashing could be related to the "Create GPS Trail" feature. Next time, when on a long trip, try not to use that feature. Alternatively, you may turn off and then turn on that feature once every hour. Periodic saving would likely achieve the same result (no-more-crashing).
2. If you are familiar with the area, you may "block roads" by using the "Avoid Area" tool. Draw a rectangle with your mouse to cover the area you wish to avoid, and then right-click inside the rectangle and select "Avoid Area". Alternatively on the menu bar go to Route > MoreOptions > Segments > PreferredRoads > PreferredRoadTypes, and there experiment adjusting likes/dislikes for different road types.