Comment 73 for bug 762203

well I discovered that OS hangs during boot and services are not started from system V
So it was not possible to shut down the computer as well
after deinstallation of plymouth everything was working
plymouth is just the fancy boot screen, so no function problem.
be aware mountall is depending on the plymouth, which might be not correct as well

Solution for me was:

dpkg --force-depends -P plymouth

I did this after upgrading to 11.10. (beta), tried to solve the problem with the upgrade unsuccessfully