ok, i uninstalled the whole thing except the comments and reinstalled it with 4 beta2 again.
i use my own template on the normal pages and the modern template on my arcade pages. no matter where i try to insert comments now, the comments are stored in the database, and when i refresh they will be shown. unfortunately every press on the send button gives me an error "Anfrage fehlgeschlagen" and in the commentbox there is some html code like this:
<?xml version="1.0" standalone="yes"?><post><after>90</after><published>1</published><noerror>1</noerror><debug></debug><id>91</id><body><![CDATA[
<ul id='post91' style='margin-left:0px;'>
<li class='post'>
<a name='josc91'></a>
<div class='posthead'>
<span class='postinfo'>
<span class='postnotify1' title='bei Antwort benachrichtigen'></span>
|<span class='postusertype'><span class='administrator'>SAdministrator</span></span>
|<span class='postdate'>2009-08-27 08:41:26</span>
</span>
<span class='username'>
<a href='/index.php?option=com_comprofiler&task=userProfile&user=62'>Pucki</a>
</span>
- <span class='posttitle'>wert</span>
</div>
<div class='postcontent'>
<div class='comment_avatar'><a href='/index.php?option=com_comprofiler&task=userProfile&user=62'><img class='avatar' src='
www.lossmerfiere.de//images/comprofiler/tn62_4a7149a3dd371.jpg
' alt='avatar' /></a></div><div class='comment_content'>wertwertwertwertwert</div>
</div>
<div class='postfooter'>
<ul class='voting'><li><a id='yes91' class='voting_yes' href='javascript:JOSC_voting(91,"yes")'>0</a></li><li><a id='no91' class='voting_no' href='javascript:JOSC_voting(91,"no")'>0</a></li></ul>
<span>
<a href='javascript:JOSC_reply(91)'>Antworten</a><a href = 'javascript:JOSC_quote(91)'>Zitat</a><a href='javascript:JOSC_editComment(91)'>Bearbeiten</a><a href='javascript:JOSC_deleteComment(91)'>Löschen</a>
</span>
</div>
<div class="josc_clear"></div>
</li>
</ul>
]]></body></post>