c# program closes and restarts if I run the .exe by double click or cmd

Hello I have a weird bug in my application.

I have build an c# script which opens a form. Well if I run the .exe from visual studio everything works great but if I run the .exe by doubleclick or from the cmd the program stays for 5-10 seconds and than restarts the form again and stays untill I close the programm. The project is a windows forms application.

My Main looks like this:

static int Main(string[] args)
        {
            using (StreamWriter w = File.AppendText(@"pathToLog\log.txt"))
            {
                string currentProject = GetCurrentProject();

                if (currentProject == "project")
                {
                    if (args.Length > 0)
                    {
                        startType = args[0];
                        Log("Commandline argument" + args[0], w);

                        if (startType == "-param1")
                        {
                            Log("In param1!", w);

                            Application.EnableVisualStyles();
                            Application.SetCompatibleTextRenderingDefault(false);
                            Application.Run(new Form1());

                            Log("Out of param1!", w);

                            return 1;
                        }

                        else if (startType == "-param2")
                        {
                            //do some stuff
                            return 2;
                        }
                    }
                }

                return 0;
            }
        }

What do I miss? Of course I am giving the cmd the right params to start the form.