Random solid squares appearing in pdf

Question

I have these random solid squares appearing in my pdf files for no reason. I tried to isolate the problem and relate it to a particular type of command. But, I still see them from time to time regardless of what commands I use. Here is an example of a simple TeX input.

\begin{itemize}
\item Outer item 1.
\begin{itemize}
\item The code is easy to read/understand given the comments/documentation.
\end{itemize}
\end{itemize}

And below is a snapshot of the pdf that is generated. The funny thing is if I make the text sentence in the inner itemize shorter, it doesn't appear in this case.

I am using Tex Live 2015 on OS X, El Capitan.

Answer 1

The black boxes are generated by overfull \hboxes if \overfullrule is set. This is usually done by class option draft.

Solution:

• Solve the problems with the overfull \hboxes.

  Here, \slash instead of / make it easier for TeX to find hyphenation points:

  comments\slash documentation.
  

  or even

  comments\slash\hspace{0pt}documentation.
  

Workaround:

• Remove option draft from the class option list.

• Or set \overfullrule to zero:

  \setlength{\overfullrule}{0pt}