I’ve been creating slightly modified CentOS netinstall ISO images using the following steps: Copy contents of CentOS netinstall ISO image to a temporary directory Edit isolunux/isolinux.cfg file Create new ISO image using the following command: mkisofs -o new.iso -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -R -J -v -T /tmp/iso I’ve been using that command for many years and found it in the RHEL 5 documentation I believe. Anyway, so far, so good. If I burn a CD from this new ISO image I can boot from it and get the modified menu as expected. However, if I use dd to copy this ISO image to a USB stick, It’s not bootable. Using the exact same dd command with the original CentOS ISO image produces a bootable USB stick. Any idea why my modified ISO image is not bootable when copied to a USB stick? Alfred