installation detects wordpress already installed

Hi,
I installed my blog first time and it worked except that it had to have http://www.address.com/wordpress for it to show up. So I removed everything, started again and installed it directly taking out the wordpress folder. I am trying to run the install.php as per the instructions but it says ‘already installed You appear to have already installed WordPress. To reinstall please clear your old database tables first.’

Any ideas on how to fix this?