After upgrading my Ubuntu machine from ver. 11.10 64-bit to 12.04 64-bit, I get the following error and the machine stop working before any graphical environment:

** (plymouthd:357): WARNING **: Command line `dbus-launch --autolaunch=530c973a1fe4d1e1e6bd... --binary-syntax --close-stderr' exited with non-zero exit status 1: Autolaunch error: X11 initialization failed.\n udevd[397]: specified group 'colord' unknown The disk drive for / is not ready yet or not present. Continue to wait, or Press S to skip mounting or M for manual recovery.

Any help appreciated.