The Harvester normally runs as a service. You can check the service status from the Control Panel | Services applet, or look for the process named "Kiwi_Harverster.exe" in the task manager.
The Harvester creates a log file when it runs called Kiwi_Harvester.log situated in the install folder. Check the log file for any messages that might indicate that there is a problem.
To run the program interactively instead of as a service, use the -interact command line option.
C:\Program Files\KiwiHarvester\Kiwi_Harvester.exe -interact