Invalid class Exception is thrown from powershell

Question

I am getting the following exception from powershell console, when I try to query an Exchange server 2007 which is hosted in Windows Server 2003.

Invalid class + CategoryInfo : InvalidOperation: (:) [Get-WmiObject], ManagementException + FullyQualifiedErrorId : GetWMIManagementException,Microsoft.PowerShell.Commands.GetWmiObjectCommand

Here is the query, which I have tried

It would be great, If someone could shed some light into this issue.