TopRank may temporarily use up to 10 MB of hard disk space (or more, for very large models) to write temporary files. Before running TopRank, you should check that you have at least this amount available, plus room to save spreadsheet and simulation files, as well as any space that you are using for virtual memory. For example, if you have assigned 20 MB of space to virtual memory (type: temporary), you should have at least 30 MB of available hard disk space to run TopRank, plus additional room to save any simulation files.