Thank you sir,
I created a php file named cookie.php which I uploaded to my root which, when I browsed to it provided me with:
Cookie Domain: .subtlephotos.com
Cookie Name: phpbbs_xxxxx
Cookie Path: /
Cookie Secure: Not checked
Force Server Vars: Not checked
Script Path: /
Server Name: www.subtlephotos.com
Server Port: 80
Server Protocol: http://
Purged the cache from the General Tab and manually cleared the cache folder except got ".htaccess" and "index.htm". (also cleared the browser history & cookies Google Chrome) restarted the browser and still had the sid appear on the address bar following the site address.
Took a chance and went through the process once again and renamed the cookie by changing the last 5 characters. I was then able to successfully installed AutoMod without any errors.
The solution I scrounged up was successful hope it'll help others.