I have Ubuntu 12.04 installed on a bootable USB drive. It works well with 2 laptops (meaning, laptops boot successfully off the USB drive). However, when I connect the USB drive to a HP EliteBook 8540w I get the following message:
hd0 out of disk grub rescue>
Why does it even check hd0?? I went over all the BIOS options and couldn't find anything obvious to cause it. To be clear, I did change the boot order in the BIOS to USB device first.
I found a post (can't remember where...) that explained how to recover from grub rescue and the following commands work for me and allow me to boot off the USB drive: set prefix=(hd1,msdos1)/boot/grub set root=(hd1,msdos1) insmod linux linux /vmlinuz root=/dev/dsb1 initrd /initrd.img boot
But I don't really want to type this every morning when I boot up my laptop :-(