Problem installing latest wordpress in to subdomain

Hi there.
I was hoping someone might spill some light on the issue.
I have a website that is running latest wp 3.3.1. Today I decided to install another instance of the wordpress in to the sub folder. I created a folder inside of the root of my main website and created separate database. Then I ftp’d wordpress files and installed wordpress. SO now I should of had http://mymainsite.com and http://mymainsite.com/secondsite/
Installation went well and everything is fine except when I try to visit http://mymainsite.com/secondsite/ the script is trying to install itself over again.
Both sites have a permalink %postname%
Both sites are running latest wordpress.
If I go to http://mainsite.com/secondsite/wp-admin I can log in to the admin panel just fine. But the script is keep on trying to install again when I visit second site root.

Please somebody help.