get-vmhost error "Client found response content type of '', but expected 'text/xml'"

Getting below error while running get-vmhost. any idea?

PowerCLI C:\Windows\system32> Get-VMHost |fl
Get-VMHost : 1/30/2013 2:10:35 PM    Get-VMHost        Client found response content type of '', but expected 'text/xml'.
The request failed with an empty response.
At line:1 char:11
+ Get-VMHost <<<<  |fl
    + CategoryInfo          : NotSpecified: (:) [Get-VMHost], ViError
    + FullyQualifiedErrorId : Client20_QueryServiceImpl_RetrievePropertiesEx_ViError,VMware.VimAutomation.ViCore.Cmdlets.Commands.GetVMHost