When I run Kana Dynamic IP Updater as service in Windows Vista, the tray icon is not displayed.

Windows Vista changes how the service is run. In previous version of Windows, all services are run in session 0 together with applications, where session 0 is the same session as the first user who logs on to the console. This means session 0 is interactive, and the service has, in simplified term, the same resources as the application. This design is believed to be a security risk.

In Windows Vista, session 0 is changed to become noninteractive. Services are only run in session 0. The first user logs on to the console will be given session 1, and so on. All applications will run on session 1 and above.

Kana Dynamic IP Updater that is configured to run as service will run at session 0, and because this session is noninteractive, any attempts to create a user interface (UI), such as tray icon will fail.