The point of the error is still not clear to me. At what stage of the boot process does the problem start? Have you followed the right directions when you created the USB image? Have you tried the image on some other PC, just to validate its usability? When prompted to boot FreeBSD (if you reach that stage), try with other options (like disabling ACPI, etc) just to see if your system boots them. After you get the error, what does your system do? It just halts?