Most of the time trouble booting USB hybrid image

[Kay Hannay <klinux@hannay.de>]

Hello,

I'm using Debian Wheezy in a VirtualBox VM on a Debian Testing host
system (at the moment more or less same as Wheezy). In the Wheezy VM
I create a live-build 3.0.5-1 based ISO hybrid image for a small
custom distribution for a very special use case.
My problem is that the generated hybrid image most of the time is
not bootable. I always run a "lb clean" and then "lb build" with my
custom configuration in the VM. Then I copy the resulting
binary.hybrid.iso to the host system via a VM shared folder and run
"dd if=binary.hybrid.iso of=/dev/sdc" and one or more "sync". When I
try to boot from the USB stick, the system hangs in the BIOS, the
HDD LED is lighted forever. But this is not always the case.
Sometimes I can boot from the USB stick without a problem. In case
the image is not bootable, I can run the image as ISO image in
VirtualBox without a problem. So the ISO seems to be OK.
I have no idea, how to fix this problem. I have tries other USB
sticks, other PCs, run dd as root, nothing helps.
Does anybody here have an idea for me?

Thanks!

Best regards
Kay