Can't compile XeLaTeX document with biblatex and gb4e together

Question

The following document will not compile (using xelatex, biber) if the package gb4e is activated. If you comment out the gb4e package it works fine:

\documentclass{article}
\usepackage{fontspec}
\setromanfont{Times New Roman}
% \usepackage{gb4e} % <-- FAILS WITH THIS PACKAGE ACTIVATED

\usepackage[nopar]{lipsum} % for dummy text
\usepackage[american]{babel}
\usepackage[authordate,isbn=false,backend=biber]{biblatex-chicago}  

\begin{filecontents}{\jobname.bib}
@book{Saussure1995,
    Author = {Ferdinand de Saussure},
    Origyear = {1916},
    Publisher = {Payot},
    Title = {Cours de Linguistique Générale},
    Year = {1995}}
\end{filecontents}
\addbibresource{\jobname.bib}

\begin{document}
\section*{Les Présentations}
\lipsum[1] \autocite{Saussure1995}   
\printbibliography
\end{document}

Any help would be greatly appreciated.

Answer 1

In the gb4e.sty package one finds this comment:

    %  This file allows _ and ^ to be used in ordinary text, hence must be
    %  loaded AFTER any file that uses them in their TeX meaning. Hence
    %  cgloss(n).sty is loaded early in this file.  This feature is known to
    %  cause some problems with other packages, but is maintained for backward 
    %  compatibility. If you have problems, you can try disabling it by
    %  placing the command \noautomath immediately after loading the gb4e package.
    %  [Added 2009/12/28]

The definition it gives of the active underscore is

% \automath     Make _ and ^ work outside math mode
% \noautomath   Restore normal sub/superscript behavior

{ % Temporarily change catcodes
  \catcode`\_=\active
  \catcode`\^=\active

  \global\def\automath{%
    \catcode`\_=\active
    \catcode`\^=\active
    \def_##1{\gb@ifnextchar^{\automath@two_{##1}}{\ensuremath{\sb{##1}}}}%
    \def^##1{\gb@ifnextchar_{\automath@two^{##1}}{\ensuremath{\sp{##1}}}}}
}
\def\automath@two#1#2#3#4{\ensuremath{#1{#2}\relax #3{#4}}}
% Restore default catcodes for ^, _
\def\noautomath{\catcode`\_=8 \catcode`\^=7 }

which is, in my opinion, bad. Indeed the package authors thought it better to provide a way for disabling it. In any case, when \automath is enabled (which it is by default), the underscore cannot be used in labels.

So my best advice is doing

\usepackage{gb4e}
\noautomath