title: Working copy of 'c:\folder' locked. Attempt to write a readonly database
body: <p>I'm new to tortoise... When I try to run SVN update on c:\folder on Windows Server 2008 R2, I get the error messages:</p>
  
  <ol>
  <li>"working copy of 'c:\folder' locked.</li>
  <li>attempt to write a readonly database</li>
  </ol>
  
  <p>It seems like I need to change file / folder permissions... What do I change them to?</p>