Hi, I've got similar problem, when I add to vhost the following line
AddOutputFilterByType LAYOUT text/html
Nothing appears in WebPage and in error log
but when I change "LayoutFooter footer.html" to "LayoutFooter somenonexisting.dir" then in log appears that error
[Thu Sep 09 13:01:23 2010] [error] [client 192.168.20.1] The following error occured while processing the Layout : 404
[Thu Sep 09 16:17:33 2010] [error] [client 192.168.20.1] File does not exist: /var/www/test.qpa/web/somenonexisting.dir
Thanks for your time!