The issue you are experiencing stems from a security setting in cPanel which prevents PHP scripts from running if the PHP file itself, or the directory it is in, is writable by group or global users.
You can correct this by removing write permissions for all directories on your website except for the following:
/cache/
/configs/
/files/
/images/
/modules/
/tmp/
/tmp/tplthumbs/
/templates/
