Threading problem

Jeg har en proces der skal opdatere min GUI, men får denne exception:

Cross-thread operation not valid: Control 'textBox1' accessed from a thread other than the thread it was created on.

Proces.cs >>

//declaring the event handler delegate
    public delegate void ValueChangedEventHandler(object source, double Value);

    public class Process
    {
        bool isAlive = true;

        public Process()
        {
            Thread thread = new Thread(new ThreadStart(Run));

            thread.Start();
        }

        //declaring the event
        public event ValueChangedEventHandler ValueChanged;

        public void Run()
        {
            Vaegt_Fase fase = new Vaegt_Fase();

            while (isAlive)
            {
                Vaegt_Fase.VaegtFase_Vaerdier current_Fase = fase.Run(15,10);

                if (current_Fase.State == FaseState.Approved)
                    ValueChanged(this, current_Fase.Value);
                /*if (current_Fase.State == FaseState.NotApproved)
                    ValueChanged(this, current_Fase.Value);*/
                if (current_Fase.State == FaseState.Working)
                    ValueChanged(this, current_Fase.Value);

                Thread.Sleep(1000);
            }           
        }
    }

Form1.cs >>

public partial class Form1 : Form
    {
        Entity.Process proces;

        public Form1()
        {
            InitializeComponent();
            proces = new Entity.Process();
            proces.ValueChanged += new Entity.ValueChangedEventHandler(proces_ValueChanged);
        }

        void proces_ValueChanged(object source, double Value)
        {
            textBox1.Text = Value.ToString(); // Exception kommer her.
            //MessageBox.Show(Value.ToString());
        }
    }