Один экземпляр приложения

namespace SyncServiceController

{

static class Program

{

[STAThread]

static void Main()

{

bool onlyInstance;

Mutex mtx = new Mutex(true, "SyncServiceController", out onlyInstance);

if (onlyInstance)

{

Application.EnableVisualStyles();

Application.SetCompatibleTextRenderingDefault(false);

Application.Run(new frmMain());

}

}

}

}