title: Lost the ability to fold code in eclipse
body: <p>I have lost the ability to fold my code in Eclipse (Helios).</p>
  
  <p>I have always used <kbd>ctrl</kbd> + <kbd>Shift</kbd> +  <kbd>/</kbd> but now it's not doing anything in one particular project and also all the "+" signs have vanished from the left bar.</p>
  
  <p>Can anyone tell me what I have done?
  In another project it's fine, but the one I'm currently working on I can't and it's so frustrating!</p>