I've installed Ubuntu Desktop 13.04 32bit. Next I configured /etc/grub.d/40_custom to boot live system from ubuntu.iso (also Desktop 13.04 32 bit) I used configuration:

menuentry "Ubuntu 13.04 Desktop" {
 loopback loop /boot/ubuntu.iso
 linux (loop)/casper/vmlinuz.efi boot=casper iso-scan/filename=/boot/ubuntu.iso noeject noprompt splash --
 initrd (loop)/casper/initrd.lz
}

and it works OK.

Later I made some changes on my installed ubuntu. I made some configuration, installed additional packages and so on. After that I made backup using remastersys tool. Remastersys gave me new ISO file. So I wanted to use it. And here was first problem. Remastersys creates only initrd.gz file. So I changed the grub configuration

form:

  initrd (loop)/casper/initrd.lz

to:

 initrd (loop)/casper/initrd.gz

But after that, when I reboot my system I get error:

/init: line 3: can't open /dev/sr0: No medium found

Any ideas how to fix it?

Best Regards, Bartosz