If somehow you have broken the APT package handling utility and you get this error:

ed@niobe:~$ sudo apt-get install xchat
E: dpkg was interrupted, you must manually run 'dpkg --configure -a' to correct the problem.

Then when you run  ‘dpkg –configure -a’ you get this error:

ed@niobe:~$ sudo dpkg --configure -a
Processing triggers for libc6 ...
ldconfig deferred processing now taking place
dpkg: ../../src/packages.c:221: process_queue: Assertion `dependtry <= 4' failed.
Aborted

This is how I fixed it.

I went to the Synaptic package manager -> Settings -> Preferences -> File -> Delete cached packaged files

Then Edit -> Fix Broken packages

Hope this helps someone ^_^