multithreading - Threads C# application crash -

hi guys i'm having problems c# , threads, i'm new this, i'm doing wrong?

public system.windows.forms.textbox text_box;  public static thread object_t = new thread (); public static thread worker_thread = new thread (object_t.execute_t);   public imagine_test () {     initializecomponent (); this.text = "title"; } private void initializecomponent () { this.text_box = new system.windows.forms.textbox (); this.suspendlayout (); this.text_box.name = "text_box"; this.text_box.location = new system.drawing.point (5, 5); this.text_box.multiline = true; this.text_box.height = 50;     this.text_box.width = 500; this.text_box.borderstyle = 0; this.clientsize = new system.drawing.size (510, 60); this.controls.addrange (new system.windows.forms.control[] { this.text_box }); load_func (); this.resumelayout (false); }  public static void main () { application.run (new imagine_test ());           }  public void load_func () { text_box.appendtext ("lorem"); worker_thread.start ();  while (!worker_thread.isalive);     thread.sleep (1);     object_t.opreste_fir1 ();     worker_thread.join ();     }  }   public class thread : imagine_test  {       public void execute_t ()   {     while (!_shouldstop) {         //thread.sleep(5000);         // run code         text_box.appendtext ("some text");      }  }   public void opreste_fir1 ()  {       _shouldstop = true;  }   private volatile bool _shouldstop; 

you can't access control's members different thread 1 created it.

this line cause exception:

 text_box.appendtext ("some text"); 

you need marshal call user interface thread:

 text_box.invoke(new action( () => text_box.appendtext("some text") ) );