When deploying a Windows 7 64-bit image from our deployment server (using Microsoft Deployment Toolkit, or MDT), we would run into an error message after the image had been applied to a workstation:
Windows could not parse or process the unattend answer file [C:\windows\Panther\unattend.xml] for pass [specialize]. A component or setting specified in the answer file does not exist
It turned out that Internet Explorer 10 had been installed. To fix the issue, you need to remove the IEWelcomeMsg entry from the answer file (either by editing unattend.xml manually on the server for the task sequence, or using Windows System Image Manager (WSIM).
This post clued me into the issue.