You are seeing Internal Server Errors in your browser when you view your web site.
You have recently added items to your .htaccess file that contain php_flag and/or php_value directives.
Example items in your cPanel error log (cPanel > Error log) will be like:
Invalid command 'php_flag', perhaps mis-spelled or defined by a module not included in the server configuration
The script you are using assumes that PHP is installed as a module. PHP is installed as a CGI on our servers. Your script should have documentation for how to install it on servers that run PHP as a CGI. This is sometimes referred to as PHP SuExec or SuPHP.
Instead of adding these directives to your .htaccess file, add them into a file called php.ini and place this file in the same directory that your script runs in. Most often this will be public_html, but in some cases you will install your script in a subdirectory. Wherever your script runs, this is the place for your php.ini file. You will need to drop the "php_flag" and "php_value" prefix. You will also need to put an equals (=) sign between the setting and the value.
For example, if your script recommends these settings in a .htaccess file:
php_flag register_globals off php_flag magic_quotes_gpc off php_value safe_mode off
Put them in a php.ini file instead. Here is the proper syntax:
register_globals = off magic_quotes_gpc = off safe_mode = off