Another solution is to disable DEP in the BCD-store of your USB-device. This can be done by following theses few steps : Boot a system into PE from your USB-stick (disable DEP in the bios if needed) from the PE command prompt type : - "bcdedit /store [your USB-stick driveletter]\boot\bcd" - this will give you the contents of the BCD-store on your USB-device - locate the entry "Window Boot Loader", there you'll find the value "identifier", wich - in my case - has the value {default}. (this could also be {Current} in your case.) - type "bcdedit.exe /store [your USB-stick driveletter]\boot\bcd /set {default} nx AlwaysOff" (replace {default} with {current} if needed.) - reboot your system and restore the BIOS-setting to it's original value. This disables the Windows PE DEP-functionality completely without messing around in the BIOS. This sollution will not only work on the HP DC7800, but also in other systems. greets, Peter