did a restart of apache, and still same problems, just really dont get how 3.0.4 would work and now 3.0.5 doing this?
Thousands of lines of code have been changed or added and the new setup is stricter and more secure, so this can lead to problems. We did not had such a problem in our tests, I will add your problem to our bugtracker so we can test it on centos 6.3 again.
What you can do as a workaround is to edit the /etc/httpd/sites-enabled/000-ispconfig.vhost file and remove the # in fron of the line:
# <IfModule mod_php5.c>
and restart apache.