login screen continually repeats

I just did a fresh install of WordPress on top of a fresh install of XAMPP on my local WinXP machine. The installation appeared to proceed correctly and I can see the default first post when I browse to http://localhost/blog/.

However, I can’t seem to get past login.php. If I browse to …blog/wp-admin, I’m directed to wp-login.php?redirect-to=wp-admin. After entering my user name and password, I click the “Login” button, and the login screen is re-displayed with the same url.

I have followed the steps in http://codex.wordpress.org/Login_Trouble but can’t get past this problem. BTW, the fresh wp-config.php already has $user_login = $user_data->user_login;, so replacement was not appropriate.

My config: WinXP Pro, SP2; XMAPP 1.4.14 (PHP 4.3.11); FireFox browser (Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.5) Gecko/20041107 Firefox/1.0)

Can someone help me please?

Thanks!