Comment 26 for bug 360378

Found a new fix...

Had ried a couple of the solutions above:
- added root delay to grub.conf / kernel boot options
- changed grub to reference the root drive directly instead of by UUID
- copied "initrd.img-2.6.32-21-generic" from another machine running Lucid
... but neither of those worked

However, after copying the initrd.ing from the bootable USB (Lucid Netbook Edition) I had used to perform the installation on this machine, then the problem was resolved - machine booted successfully and quickly as expected, instead of going to the busybox screen

Here's the file that was copied from the Live USB / installer, onto my machine (into /boot) :
  13513060 2010-05-02 22:11 initrd.img-2.6.32-21-generic

Many thanks to this excellent doc, which got me on the path of this fix.
--> http://www.dedoimedo.com/computers/ubuntu-initrd-bug.html