After new start of the system I did not get the error message any more, but the boot process stops. But there had been some other update meanwhile as well.
I see that the screen is triggered because it is not as dark as it is when switched off. If i remove the splash option in grub dialogue system starts as normal.
@Martin: after sudo dpkg-reconfigure plymouth I got:
update-initramfs: Generating /boot/initrd. img-2.6. 35-28-generic
After new start of the system I did not get the error message any more, but the boot process stops. But there had been some other update meanwhile as well.
I see that the screen is triggered because it is not as dark as it is when switched off. If i remove the splash option in grub dialogue system starts as normal.