I'm getting an problem having a site for the reason that it appears like my htaccess file (located in web root) is stopping use of any php files in subdirectories. I have examined this by developing a new test folder and adding a php file into it which does an easy echo. I usually obtain a 500 error.

This problem only lately began happening. The htaccess rules I've overlap with a number of other sites I run by myself server, however that one website is located with a different company. Does anybody know why this may be happening? Could a big change around the server have triggered this possibly?

This really is my htaccess file:

<IfModule mod_deflate.c>
AddOutputFilterByType DEFLATE text/text text/html text/plain text/xml text/css application/x-javascript application/javascript

# Turn on URL rewriting
RewriteEngine On

# Put your installation directory here:
# If your URL is www.example.com/kohana/, use /kohana/
# If your URL is www.example.com/, use /
RewriteBase /

# Protect application and system files from being viewed
RewriteCond $1 ^(app_admin|app_public|system)

# Rewrite to index.php/access_denied/URL
RewriteRule ^(.*)$ index.php/access_denied/$1 [PT,L]

# Do not enable rewriting for other files that exist
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d

# Rewrite to index.php/URL
RewriteRule ^(.*)$ index.php/$1 [PT,L]

Options -Indexes

See this discussion from ServerFault. It's certainly a permissions problem. Per that discussion, make certain parents folders also provide the correct permissions or Apache can't descend in to the folder using the .htaccess file to see it.