SCOM 2007 : The error is 0x80FF0066(0x80FF0066).
Hi Guys,
First day back to work after the Xmas holidays and first error of the year
Below 3 events that I found on a customer server, that was not reporting to Operations Manager anymore.
Event Type: Error
Event Source: HealthService
Event Category: Health Service
Event ID: 1220
Date: 1/3/2012
Time: 4:22:36 PM
User: N/A
Computer: xxxx
Description:
Received configuration cannot be processed. Management group "xxxx". The error is 0x80FF0066(0x80FF0066).
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Event Type: Error
Event Source: HealthService
Event Category: Health Service
Event ID: 7022
Date: 1/3/2012
Time: 4:22:35 PM
User: N/A
Computer: xxxx
Description:
The Health Service has downloaded secure configuration for management group xxxx, and processing the configuration failed with error code 0x80FF0066(0x80FF0066).
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Event Type: Warning
Event Source: HealthService
Event Category: Health Service
Event ID: 7004
Date: 1/3/2012
Time: 4:22:35 PM
User: N/A
Computer: xxxx
Description:
The Health Service received a secure message from management group xxxx which was encrypted using the wrong public key. This message has been discarded and the public key will be re-published.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

The root cause is a missing registry key on the server. Take a look to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HealthService\Parameters\Management Groups\UCBOM2007\SSDB\References
On the non working server :

On a working server :

When you compare the both servers, you notice that the following registry key is missing :
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HealthService\Parameters\Management Groups\xxxx\SSDB\References\92f8f803-0763-f491-2480-274bfc4126f9]
@="01020202020202020202020202020202020202020200000000000000000000000000000000000000" Just import the missing registry key from the working server to the non working server, and after a few seconds, the event below will appear, problem fixed 
Event Type: Information
Event Source: OpsMgr Connector
Event Category: None
Event ID: 21025
Date: 1/3/2012
Time: 4:28:37 PM
User: N/A
Computer: xxxx
Description:
OpsMgr has received new configuration for management group xxxx from the Configuration Service. The new state cookie is "24 58 21 8C 7C D4 70 68 B2 87 1A 52 EA BE 7F 66 43 10 FC A7 "
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

If you want more information about this issue, I invite you to read the two followings posts :
http://thoughtsonopsmgr.blogspot.com/2009/02/eventid-7024.html
http://www.systemcentercentral.com/tabid/60/indexId/34058/tag/Forums+Operations_Manager/Default.aspx#vindex56241
Cheers
Christopher KEYAERT
http://twitter.com/keyaertc