title: IllegalThreadStateException on Thread Start
body: <p>Some of my users have been reporting IllegalThreadStateExceptions, which lead back to the following code. I was unable to recreate it, and most people are able to execute this part of the code with no issues.</p>
  
  <p>The code is re-executed periodically, so the old thread should be replaced by a new one and started, but that's where the error occurs.</p>
  
  <pre><code>if (head.threadSeal != null)
  {
      head.threadSeal.interrupt();
  }
  
  head.threadSeal = new ThreadFindSeal();
  head.threadSeal.start(); // IllegalThreadStateException here
  </code></pre>
  
  <p>Relevant stack trace:</p>
  
  <pre><code>java.lang.IllegalThreadStateException
      at java.lang.Thread.start(Thread.java:704)
  </code></pre>
  
  <p>Am I missing something in the documentation, why would start ever fail on a new thread?</p>