group_posts.tpl where it says:

Code:
Add New Topic:</DIV>
<DIV style="PADDING-LEFT: 20px; PADDING-BOTTOM: 5px">
It should be

Code:
Add New Comment:</DIV>
<DIV style="PADDING-LEFT: 20px; PADDING-BOTTOM: 5px">
Where it says:

Code:
join this group</a> to post a topic.[/b]
it should be

Code:
join this group</a> to post a comment.[/b]
and where it says

Code:
<INPUT type=submit value="Add Topic" name=add_topic>
it should be

Code:
<INPUT type=submit value="Add Comment" name=add_topic>