1) Remove the line with ‘00000000-0000-0000-0000-000000000000’ value in the table MonitorData.DesktopGroup on the database. This line is the first one.
To do so :
>>Go into the DBTablesMonitorData.DesktopGroup, right click, edit top 200 rows.
>>Try selecting the row on the left so everything is highlighted. Right click on it and delete row
2) Restart monitor service on both controller
3) Log in back to Director
Related Links : http://discussions.citrix.com/topic/375612-data-source-unresponsive-or-reported-an-error-view-director-server-event-logs-for-further-information/