Can't login to Admin page

Hi all,

I recently updated my blog from 3.02 to 3.1 and immediately had the IIS Infinite Redirect issue. Was able to solve that with the plug-in for that issue.

However, between Sunday night when I fixed that and this morning I lost the ability to log in to the site either as a user or an admin. I type in the user name and password and after clicking the login button the screen comes right back to the login page. If I enter a bad password or non-existing user I get the login error page as expected.

I’ve seen a bunch of posts with people having similar issues, but wanted to give a new forum post a shot without muddying up someone else’s.

I’ve tried all the potential solutions I could find in the blogs:
– Delete the plugins folder
– Use the wp-login.php file instead of wp-admin/index.php
– Use phpmyadmin to reset the password of a user account (with the MD5 option)
– Clear cache and cookies, try multiple browsers / multiple machines
– Re-copy the 3.1 install files back over the top from the zip file
– I don’t have an .htaccess file to adjust
– It’s my own server, not one from a hosting company
– Replaced the wp-login.php file with a backup
– Ensured the wp-login.php file has the correct entry for $user_login = $user_data->user_login;
– Checked the siturl in wp-options table in mysql
– I don’t have any subdomain options enabled
– No firewall changes have occurred since it was last working

It may be interesting to note that the URL for the login page changes after the failed login to:

http://www.sitename.com/wp-login.php?redirect_to=http%3A%2F%2Fwww.sitename.com%2Fwp-admin%2Fusers.php&reauth=1

I’m using Win2k Server and PHP 2.6.1 and MySQL 4.1.10. (I know… it’s in need of an upgrade).

Thanks in advance… Any ideas are welcome!
Steve