I have a background worker. Before I invoke the worker I disable a button and make a gif visible. I then invoke the runworkerasync method and it runs fine until comleteion. On the 'RunWorkerCompleted()' I get a cross thread error. Any idea why?

    private void buttonRun_Click(object sender, EventArgs e)
    {
        if (comboBoxFiscalYear.SelectedIndex != -1 && !string.IsNullOrEmpty(textBoxFolderLoc.Text))
        {
            try
            {
                u = new UpdateDispositionReports(
                    Convert.ToInt32(comboBoxFiscalYear.SelectedItem.ToString())
                    , textBoxFolderLoc.Text
                    , Properties.Settings.Default.TemplatePath
                    , Properties.Settings.Default.ConnStr);
                this.buttonRun.Enabled = false;
                this.pictureBox1.Visible = true;

                BackgroundWorker bw = new BackgroundWorker();
                bw.DoWork += new DoWorkEventHandler(bw_DoWork);
                bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
                bw.RunWorkerAsync();
                //backgroundWorker1.RunWorkerAsync();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Unable to process.\nError:" + ex.Message, Properties.Settings.Default.AppName);
            }
        }
    }

    void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        buttonRun.Enabled = true;
        pictureBox1.Visible = false;
    }

    void bw_DoWork(object sender, DoWorkEventArgs e)
    {
        u.Execute();
    }