How can I prevent launching my app multiple times?

Question

I deployed my C# WinForms application using ClickOnce installation. Everything works fine with it (after a lot of work) :), but now I\'m facing a problem:

Whenever

Answer 1

Use this code:

[STAThread]
static void Main() 
{
   using(Mutex mutex = new Mutex(false, "Global\\" + appGuid))
   {
      if(!mutex.WaitOne(0, false))
      {
         MessageBox.Show("Instance already running");
         return;
      }

      Application.Run(new Form1());
   }
}

from The Misunderstood Mutex