Windows Instalation Issue – Admin login – already installed

I have upgraded an install of WP from 2.3 to 2.5 no problem the other day and all is still working fine. Today I tried to install a new blog on the same server, but not all went smoothly. I have installed many instances of 2.3 without issues, though this one is defeating me.

The blog address is a sub-domain. The installation page renders OK and creates the DB tables no problem. I get an admin username and password, great.

Now the problems. I click to login and the page is rendered without css. It appears to work though, redirecting me to wp-admin, though the page the redirects again to:

https://***.***.com/wp%2Dadmin/install.php?step=2/wp-login.php?redirect_to=%2Fwp-admin%2F

This page is rendered properly. Though it tells me that wordpress is already installed and to drop the tables if I want to re-intall. I get no other options.

It is running on a windows box with php 5, my sql 1 and IIS 6. Like I said above, no problems installing previous versions of WP from scratch.

Anyone got any ideas?

Thanks

Marc