I dont get this.(perhaps not a fog related problem)

I have this 1 machine that fails to image.

the machine itself seems to deploy without a problem but upon reboot it hasn't!!!!!!
still the old image on the machine (orgi ally deployed with RIS, this is driving me crazy.

the machine itself is identical to 20 other machines, which all worked fine.
even got the old windows CD out and did a full format of the drive before deploying with fog......

same again, old host OS still remains on the system!
any ideas?