 <p>This usually means you are blocking the UI thread (e.g. running a long operation inside a button click handler). Instead of using the UI thread, you will generally need to offload long I/O operations to the <a href="http://msdn.microsoft.com/en-us/library/system.threading.threadpool.queueuserworkitem.aspx" rel="nofollow noreferrer">ThreadPool</a> or your own worker threads. This is not always easy to do and requires careful design and a good understanding of concurrency, etc.</p>