create a new .htaccess file inside the public_html folder with the following content

PHP Code: 
DirectoryIndex index.php
RewriteEngine on 

tell me what happens then


also check that your cgi-bin directory should be chmodded as 0755, not 0777.

---------- Post added at 07:26 PM ---------- Previous post was at 07:21 PM ----------

Take the help of the error logs files in the following any1 directory depending
on your configuration also control panel


/var/log/message
/var/log/httpd/error_logs (/var/log/lighttpd/error_log or /var/log/httpd/error_log)

access them via SSH (like putty)
do you find any ? error lines details ? inside those files ?