I'll answer myself since no one else has:
Problem turned out to be conflicting unattend.xml files - the one in the c:\windows\panther directory, from when our head office created the image, had errors.
When I deployed using a correct unattend.xml file, it errored out at the computername section, but none of the logs showed anything telltale or incorrect. Funny thing is, the errors in the unattend file in the panther directory were in the specialize pass and all related to IE settings...
We created a new image, kept the specialize pass at ONLY computername, now it's working perfectly.
Hope this helps others, took a better part of my morning!