title: Headers sent on one server, but not on the other
body: <p>I have two servers. One development server where I develop my code and one live server. </p>
  
  <p><strong>Live server</strong><br/>
  Apache 2.2.23<br/>
  DirectAdmin 1.43.3<br/>
  Exim 4.80.1<br/>
  MySQL 5.1.66<br/>
  Named 9.7.3<br/>
  ProFTPd 1.3.4d<br/>
  sshd<br/>
  dovecot 2.1.10<br/>
  Php 5.2.17<br/>
  SSL certificate<br/></p>
  
  <p><strong>Dev server</strong><br/>
  Apache 2.2.26<br/>
  DirectAdmin 1.44.3<br/>
  Exim 4.82<br/>
  MySQL 5.6.15<br/>
  Named 9.8.2rc1<br/>
  ProFTPd 1.3.4d<br/>
  sshd<br/>
  dovecot 2.2.10<br/>
  Php 5.2.17<br/><br/>
  I know my versions are not up to date, but right now I don't have the opportunity to update this.</p>
  
  <p>The code of my website is exactly the same on both servers except for the site root and database settings (password, username etc). My live server has a SSL certificate.</p>
  
  <p>For some reason on my live server I'm getting the "Cannot modify header information - headers already sent" error when I want to redirect. This problem didn't occur at all on my development server.</p>
  
  <p>How can this be happening? There could be some whitespace, but why does this only happen on one server?</p>