Just upgraded to Kubuntu 14.04. KDE Driver manager suggested to install proprietary drivers for Nvidia video card. I selected the recommended driver (331.38) and accepted. The driver manager started the installation process but hung on 81%, all I could do is to close it. After that dpkg database was left locked and inconsistent.

The process actually was waiting for a user's input. I figured that out when I later executed "sudo dpkg --configure -a". The driver installer showed the following prompt:

Configuration file '/etc/init/nvidia-persistenced.conf'
 ==> Deleted (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ?  Your options are:
    Y or I  : install the package maintainer's version
    N or O  : keep your currently-installed version
      D     : show the differences between the versions
      Z     : start a shell to examine the situation
 The default action is to keep your current version.
*** nvidia-persistenced.conf (Y/I/N/O/D/Z) [default=N] ? y

I don't remember removing that file, but in any case the driver manager must handle such user input requests properly and not hang.

Reproducible: Didn't try