title: is_writable() return false
body: <p>I'm expecting an issue with the PHP function fwrite()</p>
  
  <pre><code>$filename = 'rss.xml';  
  
  if (file_exists($filename)) {
      echo "The file $filename exists";
  } 
  
  if (is_writable($filename)) {
      $fp = fopen($filename, 'w');
      fwrite($fp, $feed);
      fclose($fp);
   }
  else{
      echo '&lt;br /&gt;not writable..';
      if(!is_readable($filename)){
      echo ' and not readable!';
      }
  }
  </code></pre>
  
  <p>Once executed the script return :</p>
  
  <pre><code>The file rss.xml exists
  not writable.. 
  </code></pre>
  
  <p>chmod for rss.xml is 755 and safemode is off.</p>
  
  <p>I'm hosted at (mt) mediatemple.com on a (dv) and the script was working fine when I was hosted on a (gs) solution.</p>
  
  <p>I can't find what's wrong =/     </p>