Now and then some grey agents SCOM.
If I look at the server it looks like the event ID 4503 in the Operations manager eventlog is connected to the agent being greyed out.
"A module reported an error 0x80070057 from a callback which was running as part of rule "Microsoft.SystemCenter.CollectPublishedEntityState.Resend" running for instance".
A restart of the service and clearing the "health service state"-folder will fix the problem.
Anyone no of a reason for why this is happening?