Operations Manager failed to run a WMI query-Invalid class

Hi Team,

may of the windows 2008 R2 sp1 and sp2 servers getting below SCOM 2012 alert. Please help me to fix the same.

SCOM version : SCOM 2012 R2

Alert: Operations Manager failed to run a WMI query
Source: server Name
Path: server Name
Last modified by: System
Last modified time: 2/6/2014 8:33:22 AM
Alert description: Object enumeration failed
Query: 'SELECT * FROM MetaFrame_Server WHERE ServerName="server Name"'
HRESULT: 0x80041010
Details: Invalid class
One or more workflows were affected by this.
Workflow name: Citrix.PresentationServer.ActiveSessions.PerformanceMonitor