title: How to raise only 1 Timer event in C#?
body: <p>How do I get a timer event to fire one at a time.
  For example I have a timer that raises an event every 10 minutes.
  The event that is raised takes 10 or more minutes to finish executing.
  I would like the timer to reset AFTER the event has finished.
  In other words I do not want to raise more than 1 instance of the event at any one time.</p>