When there is a fatal error normally RORB will have a window pop up that will give you some details as to what the problem is. The window will normally outline what data it has read in and have an error message at the bottom detailing what has gone wrong. If the window didn’t pop up for whatever reason you can view the text file in a text file editor. The file is called RORBWin.tmp and is normally stored in the same folder as the catchment, the storm or parameter file depending on your settings. This file normally isn’t of much use but can give some information for when a run has failed to start. If this file doesn’t give you any sort of information about the problem then can you send me an email with the catchment, parameter and any other input files I would need as well as some extra details about how you are trying to run RORB. My email is email@example.com.