Hi J.Clay,

Thank you for posting.

I don't know what sample you are trying with your application. But I will
give you a sample code that makes use of the Mutex class in
System.Threading namespace.

using System.Threading;

public class Form1:Form
{
   private void Form1_Load(object sender, EventArgs e)
       {
           Boolean requestInitialOwnership = true;
           Boolean mutexWasCreated = false;

           Mutex mut = new Mutex(requestInitialOwnership,
"MSFMSGUI_MUTEX",out mutexWasCreated);
           if (!mutexWasCreated)
           {                
               this.Close();
           }
       }
}

Hope this helps.
If you have anything unclear, please feel free to let me know.

Sincerely,
Linda Liu
Microsoft Online Community Support

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Hi J. Clay,

I am closely monitoring the newsgroup and I am contacting you to check the
issue status.

If the problem is not resolved or you have anything unclear, please feel
free to post in the newsgroup and we will follow up.

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Sincerely,
Linda Liu
Microsoft Online Community Support