PLOP usb won't boot USB with Hirens installed

[forealz]

Hello

I have installed PLOP 5.0.14 to a DELL 2350 via a CD installer.  PLOP comes up, but refuses to boot from a USB drive I have plugged into a usb port that has Hiren's 15.2 installed on it.
port 2: device connected.
Boot error
No boot device found, please retry it.



If I plug in another USB drive with memtest, it works fine and boots from that. (same computer, different usb drive, different software)

The Hiren's USB will boot from USB on other machines without the use of PLOP, so I know that it is working.  It just refuses to work from PLOP on the Dell 2350.  It is like PLOP doesn't recognize it.

Thank you,