In Dreamweaver 3, if you place a command file in the Configuration/Startup folder, the command runs as Dreamweaver is starting up. Startup commands load before the menus.xml file, before the files in the ThirdPartyTags folder, and before any other commands, objects, behaviors, inspectors, floating palettes, or translators. Thus, you can use startup commands to modify the menus.xml file or other extension files. You can also show warnings or prompt the user for information, but you cannot call dreamweaver.runCommand().
Similarly, if you place a command file in the Configuration/Shutdown folder, the command will run as Dreamweaver is shutting down. You can call dreamweaver.runCommand() from shutdown commands, show warnings, or prompt the user for information, but you cannot stop the shutdown process.
For more information about commands, see What are commands?