title: Eclipse: "'Periodic workspace save.' has encountered a pro‍blem."
body: <p>I'm using Eclipse Indigo on Mac 10.7.4.  While working, I get these periodic, annoying dialogs</p>
  
  <pre><code>'Periodic workspace save.' has encountered a problem.
  
  Could not write metadata for '/.org.eclipse.jdt.core.external.folders'.
  /Users/davea/Dropbox/workspace/.metadata/.plugins/org.eclipse.core.resources/.projects/.org.eclipse.jdt.core.external.folders/.markers.snap (No such file or directory)
  </code></pre>
  
  <p>I seem to be able to continue as normal, but I was wondering how I can eliminate these errors.  </p>