Any obvious reason some of the frame is missing here:
\documentclass{article}
\usepackage{color}
\usepackage{hyperref}
\usepackage{mdframed}
\begin{document}
\begin{mdframed}
\begin{enumerate}
\item Create the cumulative sum of probabilities for each care type, thus defining the interval width
\item \textcolor{blue}{for} jj=1:m \textcolor{gray}{\% where m is the number of nurses}
\item Choose care type
\item \hspace{3cm}Randomly select care length ($n$) based on care type
\item \item \textcolor{blue}{for} ii=1:n \textcolor{gray}{\% where n is the sequence length}
\item\hspace{3cm}Generate a random number $w$
\item \hspace{3cm}Check into which cumulative probability interval $w$ falls and choose the corresponding surface category
\item update ii=ii+1
\item update jj=i+1
\item \textcolor{blue}{end}
\item \textcolor{blue}{end}
\end{enumerate}%}
\end{mdframed}
\end{document}
xcolor
rather thancolor
. – Claudio Fiandrino Jul 18 '13 at 10:47