Don't mean sound resistant. Just providing background. I will look at the info provided. Both sources are great. Much appreciated, really. I will play some more.

I have searched a multitude of sites and so far nothing specific to listview and my particular problem, hence my posting. There is a lot out there though, I agree. As an FYI, I was able to handle the same exception error regarding a radio control where I needed to change the boolean state of radio component from an async process, specifically when called from event-handler OnTimerDoThis(). I did this by following some examples for a textbox from MSDN. The following is portions of code to do this: // create a delegate within the class delegate void SetRadioCallback(bool Status); private void SetRadio(bool status) { // InvokeRequired required compares the thread ID of the // calling thread to the thread ID of the creating thread. // If these threads are different, it returns true. if (this.rdoTimerStatus.InvokeRequired) { // calling and creating thread are different SetRadioCallback r = new SetRadioCallback(SetRadio); this.Invoke(r, new object[] { status }); } else { this.rdoTimerStatus.Checked = status; } } // EnableTimer() is called from the main thread and async thread // at different times, never at the same time protected void EnableTimer() { m_Timer.Enabled = true; // call SetRadio to determine which thread is calling and update this.SetRadio(true); } Now, how do I do the same for a listview? I am not really changing anything in the listview. I just want it to search in the listview items for a match on the time elapsed event.

Yes. The main thread allows the user to add, remove, modify, clear, the listview. I have a button the allows the user to Start of Stop the timer. If I start the timer, and the timer has elapsed, it will search the items in the listview for a match in the async thread event-handler OnTimerDoThis(). This is mainly for me to understand why the error occurs and how to handle the error. I plan on using something like this in the future with better functionality, but before going BIG, I need to understand the smaller stuff. If you want I can forward the file for your review thanks for the quick reply

I get an Invalid Operation Exception error because the program is trying to make a cross-thread call to a listview object that was created by the main thread. The basic operation of the program is that items can be added, removed, modified,and cleared for the listview component on the panel. If I want, I can start a timer. Meanwhile a 'listener' sits in another thread waiting for the time to elapse. On this elapsed timer event, it enters the OnTimerDoThis() event-handler. Within the event-handler, on the foreach line, the 'Invalid Operation Exception' error occurs only after an item is added to the listview, or if an item exists already. I have put a comment at the end of the line -> '//ERROR HAPPENS HERE' so that using Find will take you to that line. The purpose of the foreach is to search the listview items and indicate if it matches to a string constant. I was able to create a delegate for a radio component and able to handle the same exception error, but need to do the same for the listview. Question is how do I get around the error? FYI. I am not using the background watcher. protected void OnTimerDoThis(Object source, ElapsedEventArgs e) { // immediatly disable timer after timeout interval reached DisableTimer(); MessageBox.Show("Inside OnTimerDoThis asnyc event\n\nTimer Disabled\n\n" + "Press OK to re-enable Timer"); foreach (ListViewItem item in lvData.Items) //ERROR HAPPENS HERE { //if (sWindowTitle.StartsWith(item.Text)) if (matchString.StartsWith(item.Text)) { MessageBox.Show("Inside match string and asnyc event\n\nTimer Disabled\n\n" + "Press OK to re-enable Timer"); } } EnableTimer(); } Regards....