I apologize for always being the one to report these things..
Parted Magic will not boot properly from USB due to incorrect ISO filename within
pmagic\boot\grub4dos\grub4dos.lst
Code:
title Default settings (Runs from RAM / Ejects CD)\n * Parted Magic version: 4.9, (C) 2010, Patrick Verner\n * http://www.partedmagic.com\n * Disclaimer: Author excluded from any liability.
kernel /pmagic/bzImage iso_filename=ubcd501.iso acpi=off edd=off noapic load_ramdisk=1 prompt_ramdisk=0 rw vga=791 loglevel=0 max_loop=256 keymap=us
initrd /pmagic/initramfs
map --unmap=0:0xff
title Live with default settings (media not usable)\n Live mode intended for 128-192MB based systems.\n The Live CD medium must remain in the drive.
kernel /pmagic/bzImage iso_filename=ubcd501.iso acpi=off edd=off noapic load_ramdisk=1 prompt_ramdisk=0 rw loglevel=0 vga=791 livemedia noeject max_loop=256 keymap=us
initrd /pmagic/initramfs
map --unmap=0:0xff
title Live with low RAM settings\n Disables most daemons and other RAM-exhausting\n processes. The preferred Live option for systems\n with minimal memory (128MB of RAM).
kernel /pmagic/bzImage iso_filename=ubcd501.iso acpi=off edd=off noapic load_ramdisk=1 prompt_ramdisk=0 rw vga=normal lowram livemedia noeject nogpm nolvm nonfs nofstabdaemon nosmart noacpid nodmeventd nohal nosshd nosound nobluetooth loglevel=0 xvesa max_loop=256 keymap=us
initrd /pmagic/initramfs
map --unmap=0:0xff
title Do not eject CD (*emulators)\n Same as option 2 except for the noreplace-paravirt\n parameter, which is needed for some emulators.
kernel /pmagic/bzImage iso_filename=ubcd501.iso acpi=off edd=off noapic load_ramdisk=1 prompt_ramdisk=0 rw vga=791 noeject noreplace-paravirt livemedia loglevel=0 max_loop=256 keymap=us
initrd /pmagic/initramfs
map --unmap=0:0xff
title Alternate graphical server\n Same as option 1. except Xvesa is used by default\n instead of Xorg. (Try this option if Xorg fails.)
kernel /pmagic/bzImage iso_filename=ubcd501.iso acpi=off edd=off noapic load_ramdisk=1 prompt_ramdisk=0 rw vga=791 xvesa loglevel=0 max_loop=256 keymap=us
initrd /pmagic/initramfs
map --unmap=0:0xff
title Safe Graphics settings (vga=normal)\n Disables splash screen and console frame buffer support.
kernel /pmagic/bzImage iso_filename=ubcd501.iso acpi=off edd=off noapic load_ramdisk=1 prompt_ramdisk=0 rw vga=normal loglevel=0 max_loop=256 keymap=us
initrd /pmagic/initramfs
map --unmap=0:0xff
title Failsafe settings\n vga=normal, acpi=off, noapic, nolapic, nopcmcia, noscsi,\n nogpm, nosmart, & boots to console.
kernel /pmagic/bzImage iso_filename=ubcd501.iso acpi=off edd=off noapic load_ramdisk=1 prompt_ramdisk=0 rw vga=normal nolapic nopcmcia noscsi nogpm consoleboot nosmart keymap=us nosshd nosound max_loop=256
initrd /pmagic/initramfs
map --unmap=0:0xff
title Console (Boots to the shell)\n Normal vga, verbose kernel messages, and\n no automatic graphical environment.
kernel /pmagic/bzImage iso_filename=ubcd501.iso acpi=off edd=off noapic load_ramdisk=1 prompt_ramdisk=0 rw vga=normal consoleboot max_loop=256 keymap=us
initrd /pmagic/initramfs
map --unmap=0:0xff
ISOLinux and Syslinux menu entries appear to be correct