Aaron--thanks for posting this. Yes, for those watching at home, it is executedrt.exe that handles the actual execution of DirectRT input files. DirectRT.exe, in contrast, is simply the front end user interface (i.e., the main window with the menus and such). In fact, if you like, you can double click on executedrt.exe directly in order to run a session. DirectRT.exe won't even know it happened.