I'm wondering if anything else could be at work. I've tried all suggestions so far, and still no luck.
I just created 2 bootable cds, one using plop, and the other using the panasonic boot disc mentioned in the old hardware thread. Both cds boot fine, they see the flash drive, but when they tell it to boot, I get 'Remove discs or other media. Press any key to restart'. I get this message quiet often when trying to boot directly from the usb drive also.
I've tried different usb ports, 3 5 different usb drives, created the drives from an absolute clean install of windows, but I'm still getting random ability to boot. There is no one perfect way I can get a reliable boot (from cold boot or not).