Just thought i'd update where I am.
arag0n85's first initflashfiles.dat flashes fine with no problems.
His second, flashed OK, but it doesn't seem to run the initial setup, so no screen calibration, date/time and nothing in the Start menu.
I then tried removing a lot of stuff from the dump folder but leaving the original initflashfiles.dat untouched. I removed about 50MB, all flashed and working fine.
So I would say it looks like removing something from the initflashfiles.dat stops the initial setup.