There are a few things of interest here.
First, you said that other than F12 to PXE boot, you don't have to do anything, but you also said it prompted for name/domain. Who is prompted for the name/domain, and when/how?
Second, you should look at the panther folder to see what happens vs what you THINK happened. In there, you can see the unattend.xml file that was used, AND which sections were processed.
Third, do you select the option to use DeployAnywhere? Try NOT selecting it to see what, if any, difference that makes.
That's where I'd start - especially with that unattend.XML under c:\windows\panther. Each section will say "processed" or not, and if not, that may be what happened. If not, you can dig through the logging, OR you can look at the file to see what may have gone wrong (e.g. not closing the XML correctly for instance, or missing a tag).
One thing we've seen happen a bit lately, is that the unattend built by people are made by a microsoft tool, and then we cut and paste into it. The problem here is the architecture can get messed up. IA64 is NOT the same as AMD64 or whatever, for instance. If 3 sections are one architecture, and 2 are a different one, either 3, or 2 sections will fail to run. Just something that helped a number of our customers.
Again, that's a start. Let us know what more you find out, OH and the answers to the questions above. :D