Settings storage varies depending on platform, and in some cases can be changed during installation. I have listed the defaults below. Before you uninstall and delete, can you attach the files in the log directory? This might give us some additional information about the error you are experiencing.
Mac: ~/Library/Zimbra Desktop
Linux: ~/zdesktop
Windows XP: C:\Documents and Settings\<user>\Local Settings\Application Data\Zimbra\Zimbra Desktop
Windows 7/Vista: C:\Users\<user>\AppData\Local\Zimbra\Zimbra Desktop |