I've followed all the instructions on upgrading to 2.5 from here: http://codex.wordpress.org/Upgrading_WordPress
but once I reach the point where I need to:
" Step 2: Upgrade your installation
Visit the upgrade page. It will be at a URL like http://example.com/wordpress/wp-admin/upgrade.php. This updates your database to be compatible with the latest code, and before you do this your blog might look funny. "
it comes up with "Fatal error: Call to undefined function: wp_get_current_user() in /home/amanda/public_html/wp/wp-includes/classes.php on line 266"
... help, please?