いろいろやってたらシャットダウンできました。
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Option Explicit
Dim vmshut
Dim VMName
Dim WMIObject
Dim VM
Dim VMList
Dim vmReturn
VMName = "SERVER01"
Set WMIObject = GetObject("winmgmts:\\.\root\virtualization")
Set VMList = WMIObject.ExecQuery("SELECT * FROM Msvm_ComputerSystem WHERE ElementName='" & VMName & "'")
VM = VMList.ItemIndex(0).Name
Set vmshut = WMIObject.ExecQuery("SELECT * FROM Msvm_ShutdownComponent WHERE SystemName='" & VM & "'")
vmReturn = vmshut.ItemIndex(0).InitiateShutdown(True,"Scripted Shutdown")
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参考：
http://msdn.microsoft.com/en-us/library/cc136822(VS.85).aspx
http://crawlmsdn.microsoft.com/en-us/library/cc136893(VS.85).aspx
http://crawlmsdn.microsoft.com/en-us/library/cc703625(VS.85).aspx