I am not sure how to check the apache config files, I am using dreamhost.
I turned the rewrite off and there is no other .htaccess in above directories. The only thing that I have changed is upgrading to the new version and the only file I edited was the config file.
If I remove htaccess completely then zenphoto works but without images and links, but I do start to get the layout at least and the 500 error is gone.
`
# htaccess file for zenphoto
# NOTE: Change the RewriteBase below to the absolute path to your zenphoto directory.
<IfModule mod_rewrite.c>
RewriteEngine Off
# !!! Change this to the web path (eg: http://www.example.com/photos --> /photos) !!!
RewriteBase /zp
RewriteCond %{REQUEST_FILENAME} -f [NC,OR]
RewriteCond %{REQUEST_FILENAME} -d [NC]
RewriteRule ^.*$ - [R,L]
RewriteRule ^admin/?$ zen/admin.php [R,L]
RewriteRule ^page/([0-9]+)/?$ index.php?page=$1 [L,QSA]
RewriteRule ^page/([A-Za-z0-9-_]+)/?$ index.php?p=$1 [L,QSA]
RewriteRule ^([^/]+)/?$ index.php?album=$1 [L,QSA]
RewriteRule ^([^/]+)/page/([0-9]+)/?$ index.php?album=$1&page=$2 [L,QSA]
RewriteRule ^([^/]+)/image/(thumb|[0-9]{1,4})/([^/\\]+)$ zen/i.php?a=$1&i=$3&s=$2 [L,QSA]
RewriteRule ^([^/]+)/image/([^/\\]+)$ albums/$1/$2 [L]
RewriteRule ^([^/]+)/([^/\\]+)$ index.php?album=$1&image=$2 [L,QSA]
</IfModule>
`