title: Codeigniter: User session keeps expiring
body: <p>I'm using CodeIgniter, and I'm having a small issue with sessions. I've set 'sess_expiration' in config.php to 0 so that the user session will never expire, yet users -even myself- are still occasionally kicked out and asked to login again! (i'm storing sessions in the DB btw)</p>
  
  <p>The way I validate a user's session is by basically checking if user_id (which I've previously stored in the session is TRUE or FALSE. If it's FALSE then it asks them to login again.</p>
  
  <p>Any idea what could be forcing sessions to expire?</p>
  
  <p>Appreciate your help :)</p>