Steve,Been doing some searching on Google for the clr20r3 exception - this is what I found, with some suggestions for trapping exceptions in your code... Its a bug in your code, so you need to debug - the reason you get the event is because an exception is being thrown, but hasnt been caught - i.e. its an unhandled exception, and the default behaviour in .Net 2 for unhandled exceptions is to terminate the application and report the event.You can always add in a handler to pickup unhandled exceptions, but the root cause is the same - its a bug in your application code.Code Snippet AppDomain.CurrentDomain.UnhandledException += new UnhandledExceptionEventHandler(WorkerThreadHandler);public void WorkerThreadHandler(object sender, UnhandledExceptionEventArgs args){if (!(args.ExceptionObject is ThreadAbortException)){Exception exc = args.ExceptionObject as Exception;MessageBox.Show(exc.ToString());}}Hope this helps This is an unhandled exception report. In .NET 2.0 (unlike .NET 1.1) the appDomain will unload when there is an unhandled exception. You can wire up your app to get more information about unhandled exceptions. Take a look at this article:http://www.eggheadcafe.com/articles/20051205.asp