Upgrade to 3.0.1 caused an error

Greetings everyone,

I was upgrading a couple of blog to 3.0.1 today. Everything went well with the first one, then when I did the – wp-admin/upgrade.php on the second one and clicked “Continue” which took me to the homepage of my site where I could see the Maintenace Mode screen I activated before the upgrade started, I get this message when I try accessing my login for the admin:

Fatal error: Call to a member function add_rewrite_tag() on a non-object in /home/thegrits/public_html/wp-includes/taxonomy.php on line 289

I cannot seem to get beyond this screen. So any assistance anyone can give will be helpful. Thanks in advance for your help!