I dropped out of school during my second semester with a 2.0 gpa. I came back two years later and never got less than an A-. Mine is a more clear-cut situation than yours, I could hardly *not* mention it, but I did mention it in my SOP and had excellent results (see the profile thread). If you have genuine reasons and it is something that will really stand out in your application, then mention them, but don't dwell on them. Stay positive, and focus on what you learned. Everything you write should show how you are a better candidate for grad school. Keep it brief, keep it positive, don't make excuses, you should be fine. My opinion only, of course.