# gb4e package causing capacity errors

I was using this:

http://www.essex.ac.uk/linguistics/external/clmt/latex4ling/examples/gb4e/

To try and create numbered examples in my document.

However, when I load it and put the example exe in that link in one of the separate Tex files (Introduction.tex) I include in main.tex, I get:

./Chapters/Introduction.tex:14:
TeX capacity exceeded, sorry [parameter stack s
ize=10000].
\gb@ifnextchar #1#2#3->
\let \reserved@d =#1\def \reserved@a {#2}\def \reserv...
l.14 ... and political news \cite{washington_post}
.  More importantly, when ...


Which is not even referring to the exe example I inserted but a couple of blocks of tex above it.

For info, here is my full code before my document begins:

\documentclass{report}
% [fontsize=11pt,border=5pt]
% standalone for the tree
\usepackage{forest}
% This overrides warnings like http://tex.stackexchange.com/questions/52576/difference-between-bookmark-levels-greater-than-one-what-does-this-mean
\usepackage{bookmark}
\usepackage{amsmath}
\usepackage{subcaption}
\usepackage{standalone}
\usepackage[round]{natbib}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[utf8]{inputenc}
\usepackage{hyperref}
\hypersetup{
filecolor=magenta,
urlcolor=cyan,
}

\urlstyle{same}
% Not sure why I need to use this
% \usepackage{graphicx}
% \graphicspath{ {images/} }
% \usepackage[pdftex]{graphicx}
% fontsize=11pt,twoside]{scrartcl}
% This is for numbered examples
\usepackage{gb4e}


Would appreciate some help as I feel like my Latex is very messy here.

The gb4e package redefines the underscore character so that it can be used in regular text mode. Although this is very useful for linguists, it can easily cause problems and in your case the problem is with your citation key washington_post.
The best way to solve this problem is immediately after loading gb4e you issue the command
\noautomath