On our HPs we have to disable Data Execution Prevention and SATA Native Mode. Also, if they are allowed to boot the first time into the HP setup routine it creates that weird security partition. Can you post any applicable logs?
Thanks zman - i'll check those bios settings. We have to turn off SATA mode on laptops, but not sure i've seen the setting on the desktops - i'l check anyway.
Unfortunately the logs are blank, i guess cause nothing has happened at that point.
One more thing, i went into the dos console from winpe, and manually mapped the drive and ran imagew, and it built fine.