facing problem when running Get-VMGuestNetworkInterface command as "Unable to parse script output."

Facing the below mentioned problem. can anyone help me getting resolved for this issue.

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PS C:\Program Files\VMware\Infrastructure\vSphere PowerCLI> Get-VMGuestNetworkIn

terface -VM $vm1 -GuestUser root -GuestPassword changeme

Get-VMGuestNetworkInterface : 5/20/2013 2:53:08 AM    Get-VMGuestNetworkInterfa

ce        Unable to parse script output.

At line:1 char:28

+ Get-VMGuestNetworkInterface <<<<  -VM $vm1 -GuestUser root -GuestPassword cha

ngeme

    + CategoryInfo          : InvalidArgument: (:) [Get-VMGuestNetworkInterfac

   e], ViError

    + FullyQualifiedErrorId : Client20_VmHostServiceImpl_GetVmGuestNetworkInte

   rface_UnableToParse,VMware.VimAutomation.ViCore.Cmdlets.Commands.GetVmGues

  tNetworkInterface

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thanks,

pravin