Similar problem as reported by another user. While booting, the system can't find
/dev/sda1 and so a "kernel panic: unable to mount root fs on unknown-block (0,0)" appears on screen.
I'm compiled & built kernel linux-126.96.36.199 on Ubuntu 10.04 running in VirtualBox virtual machine.
ps.: The update-initramfs, update-grub didn't work out for me.