UPS stop syncing

Hi

We recently upgraded our Sharepoint 2010 farm to CU on Aug, 2012. Everything look good, but the UPS stop working.

I have successfully restarted the UPS service (both FIM service and FIM Sync service). No error message generated in the event log when restarting the service.

The synchronization connection is configured and the assigned user is able to read the user profile in AD

We have one WFE, one App and one SQL server.

When clicking 'Start Profile Full Synchronization', the sync status is always on 'Idle'

How do I troubleshooting on this?

Thanks,

Kire