Issues updating VMware Tools with Update Manager

I recently updated a lab environment to vSphere 4 Update 2 and wanted to upgrade VMware Tools on several VMs at once.  I decided to use Update Manager to push out the VMware Tools update, and during the process discovered an issue between Update Manager and newer versions of Windows.  I didn't try any of the following with vSphere 4.1.

I remediated a folder of about seven VMs and to my surprise I saw that only a few of them actually updated.  The others simply sat there and never updated the tools, rebooted, or did much of anything.  Sorting the folder by Guest OS I noticed something - all of the VMs that did not update were running either Windows Server 2008 or Windows 7.