Event RSS Error Code
From your screenshot, I was able to test this same functionality on two test sites (a good general troubleshooting tactic!).  The problem does NOT replicate itself there.  The issue is specific to your site, or (less likely) reflects a bug in an older version of CiviCRM than the ones I'm testing.

I was able to use your link to see the exact error - and you're correct, the issue is a blank line.

Since you're using Drupal, I would look for a blank line at the end of settings.php and template.php.  I would also try testing whether the problem disappears if you change themes (preferably on a test copy of your site).  That will help you isolate whether the problem is in your theme.