Agent proxying needs to be enabled for a health service to submit discovery data about other computers

In Microsoft System Center Operations Manager 2007 SP1 you may get the error message:

Agent proxying needs to be enabled for a health service to submit discovery data about other computers

This looks like it is coming from the Root management server, but the details give you a GUID to the actual server with the error. It looks like this:

Details:Health service ( FED0B867-F9AE-ACAF-4CCF-311DD92789C9 ) should not generate data about this managed object ( 66A10C3E-EF01-28E2-6F41-E15C782B906D ).

In order to get the actual name of the monitored device you need to use PowerShell. Don't use the PowerShell that you find in Programs -> WindowsPowerShell 1.0 since this does not have the SCOM snap-in included. Go to Programs -> System Center Operations Manager 2007 -> Command shell then execute the following command. Replace the GUID with the one that your alert specifies.

Get-MonitoringObject -id:'FED0B867-F9AE-ACAF-4CCF-311DD92789C9' | ft DisplayName

Then to enable Proxying: 

Access the Administration Node and locate the agent under Agent Managed.  Right click the node you found after you execute the above command.  Select Properties.  Click the Security tab.  Check  Allow this agent to act as proxy…