If you want to start a process from a Windows service, such as Notepad.exe or a music player then you need to allow the service to interact with the desktop. If you go to the Service properties in the services.msc, you can edit this manually in the Log On tab. That's not ideal - you need to have this activated on install. For some reason there's no property which can be set for this, but CodeProject has a way of doing it via the registry.