private void Authenticate() { if ("".Equals(this.txtUsername.Text.Trim())) { this.lblError.Content = "Benutzernamen eingeben!"; this.lblError.Visibility = Visibility.Visible; return; } else if ("".Equals(this.txtPassword.Password.Trim())) { this.lblError.Content = "Passwort eingeben!"; this.lblError.Visibility = Visibility.Visible; return; } lblError.Visibility = Visibility.Hidden; progressBar.Visibility = Visibility.Visible; credentials[0] = this.txtUsername.Text; credentials[1] = MD5Hash.HashString(this.txtPassword.Password); credentials[2] = this.txtPassword.Password; BackgroundWorker authenticationWorker = new BackgroundWorker(); authenticationWorker.DoWork += Authenticate_DoWork; authenticationWorker.RunWorkerCompleted += Authenticate_Completed; authenticationWorker.RunWorkerAsync(); }