Strange error Message, maybe someone has any idea...

- when NOT logged in, this will show only somewhere within Kunena Forum page
- when logged in, whis will show on the very top of each page and Kunena Forum

Exact Error message is:

Warning: preg_match() [function.preg-match]: Unknown modifier 'r' in /.../com_sef/joomsef.php on line 174

Page is www.mmoinfos.de
Forum page is www.mmoinfos.de/forum

Thanks in advance for any help!