What component are you using to generate the pages? This code change in compenents/com_jcomments/tpl/default/tpl_comment.php may help you.
Change:
$thisurl = str_replace( 'amp;', '', $this->getVar( 'thisurl', '' ));
To:
$thisurl = $this->item->link;
I'm not sure why jcomments tries to generate the page URL for you, I guess it's nice, but it's very broken it seems.