Aplicacion "Windows Form" que se bloquea... en console Funciona

[Peterpay]

mira este ejemplo pequeño

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
textBox1.Text = e.UserState.ToString();
}

private void button1_Click(object sender, EventArgs e)
{
backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
backgroundWorker1.RunWorkerAsync();
}

void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
for (int i = 1; i < 10000000; i++)
{
backgroundWorker1.ReportProgress(1, i);
System.Threading.Thread.Sleep(1000);
}
}