Hello. I don't fully understand this terminal output so forgive the naive explanation of my problem. Every time I install something via terminal I get this output (I installed sl to produce the output:

Code:
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  memtest86+ syslinux-themes-debian syslinux-themes-debian-wheezy
Use 'apt-get autoremove' to remove them.
The following NEW packages will be installed:
  sl
0 upgraded, 1 newly installed, 0 to remove and 2 not upgraded.
2 not fully installed or removed.
Need to get 26.1 kB of archives.
After this operation, 117 kB of additional disk space will be used.
Get:1 http://http.kali.org/ /kali/main sl i386 3.03-17 [26.1 kB]
Fetched 26.1 kB in 1s (14.2 kB/s)
Selecting previously unselected package sl.
(Reading database ... 358476 files and directories currently installed.)
Unpacking sl (from .../archives/sl_3.03-17_i386.deb) ...
Processing triggers for man-db ...
Setting up linux-image-3.14-kali1-686-pae (3.14.5-1kali2) ...
/etc/kernel/postinst.d/initramfs-tools:
update-initramfs: Generating /boot/initrd.img-3.14-kali1-686-pae
/etc/kernel/postinst.d/zz-extlinux:
P: Checking for EXTLINUX directory... found.
/boot/vmlinuz-3.14-kali1-686-pae
P: Writing config for /boot/vmlinuz-3.14-kali1-686-pae...
I: os-proper disabled in /etc/default/extlinux: Skipping /boot/extlinux/os-proper.cfg
E: /usr/share/EXTLINUX/themes/debian: No such file or directory
run-parts: /etc/kernel/postinst.d/zz-extlinux exited with return code 1
Failed to process /etc/kernel/postinst.d at /var/lib/dpkg/info/linux-image-3.14-kali1-686-pae.postinst line 591, <STDIN> line 2.
dpkg: error processing linux-image-3.14-kali1-686-pae (--configure):
 subprocess installed post-installation script returned error exit status 2
Setting up extlinux (3:6.03~pre1+dfsg-1kali3) ...
P: Checking for EXTLINUX directory... found.
/boot/vmlinuz-3.14-kali1-686-pae
P: Writing config for /boot/vmlinuz-3.14-kali1-686-pae...
I: os-proper disabled in /etc/default/extlinux: Skipping /boot/extlinux/os-proper.cfg
E: /usr/share/EXTLINUX/themes/debian: No such file or directory
dpkg: error processing extlinux (--configure):
 subprocess installed post-installation script returned error exit status 1
Setting up sl (3.03-17) ...
Errors were encountered while processing:
 linux-image-3.14-kali1-686-pae
 extlinux
E: Sub-process /usr/bin/dpkg returned an error code (1)
After searching about this issue the only other suggestion I found for fixing it were
Code:
sudo apt-get install -f
and
Code:
sudo dpkg --configure -a
. Neither of these helped. What is my OS trying to do exactly and why is dpkg returning an error? How do I stop it trying to do what it's doing or stop the error occurring?

Any and all help is greatly appreciated.