Les autotask(s) das Oracle !

We had something similar with NVIDIA gfx card and 13.04. It only happend from time to time. disabling plymouth and splash screen in grub:

in file /etc/defaults/grub
set line
GRUB_CMDLINE_LINUX_DEFAULT="noplymouth"

and run update-grub afterwards.

This plymouth stuff is a pain and should be killed or fixed, just my 2cents.