Eu instalei o kernel 3.18.2 com o Cinnamon no Ubuntu 14.04.1:
john@john-G31M-S2C:~$ sudo apt-get remove -f
[sudo] password for john:
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following packages were automatically installed and are no longer required:
libvte-common libvte9 plymouth-x11
Use 'apt-get autoremove' to remove them.
The following extra packages will be installed:
plymouth
Suggested packages:
desktop-base
The following packages will be upgraded:
plymouth
1 upgraded, 0 newly installed, 0 to remove and 1320 not upgraded.
2 not fully installed or removed.
Need to get 204 kB of archives.
After this operation, 388 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
WARNING: The following packages cannot be authenticated!
plymouth
Install these packages without verification? [y/N] y
Get:1 http://ftp.us.debian.org/debian/ unstable/main plymouth i386 0.9.0-9 [204 kB]
Fetched 204 kB in 7s (26.3 kB/s)
(Reading database ... 175784 files and directories currently installed.)
Preparing to unpack .../plymouth_0.9.0-9_i386.deb ...
Unpacking plymouth (0.9.0-9) over (0.8.8-0ubuntu17) ...
dpkg: error processing archive /var/cache/apt/archives/plymouth_0.9.0-9_i386.deb (--unpack):
trying to overwrite '/lib/i386-linux-gnu/libply.so.2.1.0', which is also in package libplymouth2:i386 0.8.8-0ubuntu17
dpkg-deb: error: subprocess paste was killed by signal (Broken pipe)
Processing triggers for ureadahead (0.100.0-16) ...
Errors were encountered while processing:
/var/cache/apt/archives/plymouth_0.9.0-9_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
john@john-G31M-S2C:~$
Portanto, o dpkg está tentando sobrescrever /lib/i386-linux-gnu/libply.so.2.1.0 , que já está lá e foi trazido pelo pacote libplymouth2:i386 . Minha sugestão é desinstalar libplymouth2:i386 primeiro, depois executar sudo apt-get remove -f e depois instalar novamente o pacote que você desinstalou.
Espero que isso ajude.
O erro principal é "Os seguintes pacotes não podem ser autenticados". Então tente com o seguinte,
sudo apt-key update
sudo apt-get update
Espero que isso ajude você a corrigir o problema.