WordPress MU

Man - all sorts of problems today ..

I'm getting this error everytime I try and view all the blogs on the site in the admin menu:

Fatal error: Call to undefined function: get_users_of_blog() in /home/chingasb/public_html/wp-admin/wpmu-blogs.php on line 413

http://trac.mu.wordpress.org/wiki/DebuggingWpmu

Have you upgraded recently?

Have you done anything new recently?

I have a feeling maybe I don't have an up to date user.php? I think the problem might be I've still got a 1.0 install, but I had to overwrite soe older files I had and I did it with the latest installs, so they are probably pointing to something else..