Almost all of the problems associated with installing Updates stem from Installing the update over the previous version and The Dreamweaver Cache file in the users configuration folder.
before installing an update, in Dreamweaver CS4, go to Window -> Workspace Layouts -> Reset '<Your Lauout name>'. The Close Dreamweaver.
You should uninstall the previous version from the extension manager.
After installing the update, go to the configuration folder and delete the Dreamweaver cache file, more information can be found here:
2.0.2 will recognize menus created with a previous version, this will not be an issue.