WordPress rdirects to install.php

When anyone visits my homepage it redirects to wp-admin/install.php? .

WordPress is already installed in that site.

Now if someone visits an inner page it works fine and then suddenly the homepage also works fine.
Again if he uses a different browser problem reappears.

I have installed a fresh copy of wordpress and installed wordpress but again it redirects me to the same install.php page

I have been working on this problem since yesterday but havent been able to figure out.

I have checked and repair database too

Any help will be appreciated