I can’t access my wordpress blog panel when in WP version 3.0

I tried to upgrade my wordpress blog into version 3.0 but after that, I can’t access my blog’s admin panel anymore.

When I tried to surf my blog url, this phrase will come up:
“Fatal error: Call to a member function add_rewrite_tag() on a non-object in /home/albutra/public_html/wp-includes/post.php on line 872”

Here is my blog’s url: https://www.bloggingaccess.com

Please someone help me.

– Felix Albutra