If your BIOS can boot with the USB drive, why not use "Flash disk Install to HD" or "HD Install"?

That works fine when it works, but more often than not, I get messages saying that the boot medium is defective (though the flash drive works consistently on another machine, and I get the same messages about defective medium using a perfectly good Puppy Linux bootable flash drive). The capability to boot from USB was added only in the final upgrade version for that BIOS before it was discontinued, and so any bugs would have gone unfixed. I can only boot reliably from the DVD drive, so it would be nice to boot from the DVD and then transfer control to the external drive. But I guess that box is headed for the junk heap.