Odd problem with extern.php

When using extern.php to display a post that starts with a quote, eg.

This is normal text.

The output from extern.php is:

ockquote><div class="incqbox"><p>This is a quote</p></div></blockquote><p>This is normal text.

so you end up with the post starting:

ockquote>

Any ideas what could be causing this? Some iffy parsing?

--Alan