Bios question, Program cannot be run in DOS mode?

Hi, I am trying to fix a friend's hdd and I downloaded the latest bios for his pc. I followed this guide exactly: http://www.bay-wolf.com/bootcd-bios.htm on how to create a bootable cd with a bios.(he doesnt have a floppy drive) Everything works fine except when i get to the Z:, I type in Zname of bios update.exe) and it says this program cannot be run in DOS mode. I really dont understand why it isnt working because in the tutorial it does work.. any help would be appreciated, thanks.