Hi Colin,
As far as I know VUM doesn't support Win2k8r2 Guest OS patching, take have a look on link below, page 17
www.vmware.com/pdf/vsphere4/r40/vsp_compatibility_matrix.pdf
Besides, VUM in vSphere 4.X is the last version with guest OS patch management functionality, starting from vSphere 5 VUM will support only ESX/ESXi patch management.
Cheers
Artur
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VCDX77
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