6.0.2 should be out in mid October. There may be something else going on with this third workstation. Is there a core dump by any chance in %TEMP%\zco-cores?
Not sure what else to try -- I assume you uninstalled the connector completely, and tried again? Sometimes registry keys get left around. If you search for ZCS Connector for Outlook and get rid of any registry records with those keys, then make sure HKLM\SOFTWARE\Zimbra and HKCU\Software\ZIMBRA, then install, you should get a clean install. You can also try deleting the profile and re-creating just to be clean about the whole thing. Not sure that will help though.