Fatal error called to undefined

im upgrading from 1.5 to 1.5.1 but when I upgraded it gave me some stupid error

Fatal error: Call to undefined function: get_currentuserinfo() in /home/underbur/public_html/wp-blog-header.php on line 169

now when I try to get into the admin cp it gives me a different error

Fatal error: Call to undefined function: auth_redirect() in /home/underbur/public_html/wp-admin/admin.php on line 8

Anyone know what I did wrong?