Category feed – problem when category exluded from front page

Hi,

I’m working on a WP installation using a modified version of the Twenty-Ten theme (original setup and modifications was made by another person).

Now I need to introduce a new category (“newsletters”), make sure that all posts in this category is excluded from the front page and use the category feed together with Feedburner to create a feed for users to subscribe to.

– Creating the category was no problem.

– I also has no problem excluding the category from the front page by modifying loop.php
(“original” line <?php while ( have_posts() ) : the_post(); ?> changed to:

<?php while ( have_posts() ) :
the_post();
if (is_home()) if (in_category('Newsletters')) continue;
?>

)

– However, when I try to burn the category feed with feedburner FB gives me an error. (Or actually, FB chokes when there’s posts in the category. If the Category is empty it’s OK)

Now, I have tried exactly the same steps with another WP installation, and there it works fine.
The loop.php file on the site that fails is however modified from the “original” loop.php (used on the site where it works) – thus I suspect that the problem is here somewhere…

I also note that the “main” feed (all posts, all categories) fails when there’s a post in the newsletters category.

Also, the “choking” feed seems OK when I access it directly from a browser, eg FF.

Questions:
– Where does WP generate the feeds? How is loop.php involved?
– Any hints to resolve this?

At the moment you can find the “choking” feed at http://sail-project.eu/category/newsletters/feed/

I also attach the complete loop.php code below. Any ideas welcome!

[Code moderated as per the Forum Rules. Please use the pastebin]