Qual X Wrote: I don't have UEFI and I don't have Secure Boot in my BIOS.
I see. Then you must ensure you're following the BIOS/MBR steps.
Steve2926 Wrote: Check the BIOS configuration settings on the HP.
Also give details of what the USB drive is (type, model, size) etc.
These are sound suggestions, too.
Can you boot any LiveCD from this USB? Run 'inxi -A' in the console and report back...
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