It sounds like the uVNC service is not running properly. I would ensure the service is not running and that there are no instances of winvnc.exe running on the computer, and then try starting winvnc.exe manually.
Ensure this instance of uVNC can be connected to, and that the admin properties are viewable/settable.
If this works, then I would uninstall uVNC as a service (winvnc.exe -uninstall) and re-install it (winvnc.exe -install). If it doesn't work, then you either have a bad executable file or the configuration needs further modification. You can delete the ultravnc.ini file to ensure the configuration is clean the next time the application starts.