Comment 24 for bug 572279

Well, I have a little workaround for this: In fact, Plymouth is the source of this evil, if I can say this so in english :)
Removing plymouth made me able to login into my system again.
To do so, I followed this german wiki-page: http://wiki.ubuntuusers.de/Baustelle/Plymouth

I'll short it and translate it to you other people who need their machine for work:
Just boot up with the recovery-option in Grub, and start with a net-commandline.
Enable the repository with sudo apt-add-repository ppa:dtl131/mediahacks .
In this repository are around 2-3 modified .deb-files stored with a version-numer a bit higher than the orginal, the main-package for interest is mountall. In this modified package just the dependencies to plymouth are deleleted. So, after enabling the ppa, sudo apt-get update -ing and sudo aptitude full-upgrade, you are able to remove plymouth with just sudo apt-get remove plymouth.
After this in the article I mentioned before it is recommend to remove the quiet-line in grub.
That does all, for the time before this is being fixed in plymouth you are able to continue using your system.

Hope this helps, good evening (in Germany) to all ;)