Problem and objective assessment usually are rapresented with tree diagrams. The key problem is the root of a hierarchie in wich the others problems are related in a cause and effect relationships. Depending on the situation you can have many branchs or many levels and, sometimes, is hard to keep track of everything. A mind map can help to visualize and structure the diagram. A good and easy to use tool is FreeMind. It is an open source tool, so why you don't try it!