I have the same problem in a HP laptop with Ubuntu 'Feisty'. The problem becomes after updating initramfs-tools to version 0.85dubuntu5. My system is not able to boot with initrd images generated with this version, but dowgrading to 0.69ubuntu20, I can generate valid images for kernel 2.6.19 and 2.6.20. I think the problem is not related to kernel or udev, but only to initramfs-tools.
-- Mount Root Files System Failed https://launchpad.net/bugs/47768 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
