Hi Peter,
yep this piece of code works also fine for me. With my Windows application i
dont get a STA. Here is all my main code (application entry point).

   static class BodeMain
   {
       /// <summary>
       /// The main entry point for the application.
       /// </summary>
       [STAThread]
       static void Main(string[] args)
       {
           Application.EnableVisualStyles();
           Application.SetCompatibleTextRenderingDefault(false);

           bool ownsMutex;

           // check if no other Process using a bode device with a named
mutex
           using (Mutex mutex = new Mutex(true,
Omicron.BodeAnalyzer.CommonDefs.MidLayerCommonDefs.BodeMutexName, out
ownsMutex))
           {
               System.Reflection.Assembly assembly =
System.Reflection.Assembly.GetExecutingAssembly();

               if (ownsMutex)
               {
                   string version = "Version ";
#if DEBUG
                   version += assembly.GetName().Version.ToString();
#else
               version += assembly.GetName().Version.ToString(2);
#endif
                   SplashScreen.ShowSplashScreen(version,
assembly.GetName().Version.Revision == 1);
                   BodeAnalyzer.BodeApplication app = new
Omicron.BodeAnalyzer.BodeApplication();
                   app.ScanAndSelectFirstDevice();
                   MainFrame theMainForm = new MainFrame(app);
                   SplashScreen.SetStatus("Calibrating ...");

                   theMainForm.BodeApplication.InitDevice(false);
                   // init the form
                   theMainForm.Init();

                   if (args.Length > 0)
                   {
                       theMainForm.OpenFile(args[0]);
                   }

                   // set the stop freq to fmax (different fmax for FRA and
Bode)
                   
(theMainForm.BodeApplication.Document.TestForms[2].Test.Settings as
Omicron.BodeAnalyzer.Measurement.Sweep.SweepTest.TestSettings).SetFstopToFmax();

                   theMainForm.InitTimers();

                   SplashScreen.SetStatus("Start the Test ...");
                   SplashScreen.CloseForm();

                   theMainForm.RestorePosition();
                   theMainForm.BringToFront();

                   Application.Run(theMainForm);
                   // the test is startet in the OnMainFormLoad Handler

                   // release the mutex after closing the application
                   mutex.ReleaseMutex();
               }
               else
               {
                   ResourceManager rm = new
ResourceManager("Omicron.BodeAnalyzer.BodeAnalyzerResources", assembly);
                   MessageBox.Show(rm.GetString("MsgBoxStartUpError"),
rm.GetString("MsgBoxCaptionError"), MessageBoxButtons.OK,
MessageBoxIcon.Error);
               }
           } // end using
       }
   }

This results in a MTA and not a STA. If I create a STA thread in my main
function and execute all that code in that thread everything works fine. See
below.

   static class BodeMain
   {
       /// <summary>
       /// The main entry point for the application.
       /// </summary>
       [STAThread]
       static void Main(string[] args)
       {
           Application.EnableVisualStyles();
           Application.SetCompatibleTextRenderingDefault(false);

           Thread mainThread = new Thread(new
ParameterizedThreadStart(RunBodeApplication));
           mainThread.Name = "Bode Analyzer Suite main thread";
           mainThread.SetApartmentState(ApartmentState.STA);

           mainThread.Start(args);

           mainThread.Join();

       }

       static void RunBodeApplication(object mainArguments)
       {
           bool ownsMutex;
           string[] arguments = (string[])mainArguments;

           // check if no other Process using a bode device with a named
mutex
           using (Mutex mutex = new Mutex(true,
Omicron.BodeAnalyzer.CommonDefs.MidLayerCommonDefs.BodeMutexName, out
ownsMutex))
           {
...
}
}
}

Can you explain me that behaviour?

Thanks,
Thomas