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FileSystemWatcher watcher = new FileSystemWatcher(Environment.SystemDirectory);
            watcher.Filter = "*.txt";
            watcher.Path = @"c:\";
            watcher.IncludeSubdirectories = true;
            watcher.NotifyFilter = NotifyFilters.Attributes | NotifyFilters.Size;

            watcher.Changed += new FileSystemEventHandler(watcher_Changed);					

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public static void watcher_changed(object source, FileSystemEventArgs e)
    {
           MessageBox.Show("test", e.FullPath);
    }
       
         WaitForChangedResult result =
                                     watcher.WaitForChanged(WatcherChangeTypes.Created);					

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watcher.EnableRaisingEvents = true;