Cleansettings9.exe is a utility used to return all Dartfish settings to defaults. This includes software settings and Windows Registry entries.
No content or content metadata (such as keywords) are deleted but the list of monitored folders is restored to the Windows 'Videos' folder. Any content outside of this folder will no longer be listed in the Library. Monitored folders can be re-defined in Tools menu > Options...
Download the utility below, close Dartfish, launch CleanSettings, select "Clean All" > Close.