WordPress MU

I've got a feeling this is a stupid question and I'm missing something, but I've been trying different variations of this with the same result, so I thought I'd ask:

I'm upgrading to 1.2.2. My install is in the root directory. I've deleted everything but my .htaccess file, wp-config.php, and wp-content, and uploaded the new files.

When I go to http://site/wp-admin/upgrade.php, I get this error:
"Fatal error: Call to undefined function: auth_redirect() in /home/site/public_html/wp-admin/admin.php on line 22"

Any ideas why? I haven't seen any previous posts in regard to this.

Thanks!

I think you are supposed to update from logging in the admin panel Site Admin -> Upgrade

This way it calls wpmu-upgrade.site.php or something.

I did it that way and then when I checked the upgrade.php file it said I had nothing to update.

Hmm... I'd try that, but I can't log in, either. :( wp-login.php loads, but trying to log in gives me:

"Fatal error: Call to undefined function: wp_get_current_user() in /home/site/public_html/wp-includes/capabilities.php on line 446"

I've GOT to be missing something obvious, methinks. (This was after completely re-loading a backup, deleting everything except .htaccess, wp-content, and wp-config.php, and re-uploading the upgrade files...)

Anything else I can look into?

Ok, ok. I think I'm good -- the ONLY other thing that I wasn't modifying was the wp-contents folder, so I chucked mine and replaced it with the clean one from the upgrade files, and everything worked fine.

Must've been something I had done in there. Now, to start replacing files until it breaks! :(

SPECULATION: The problem was caused by a plugin (i.e. Widgets). Since this is now part of the core package, WP does not like finding it in Plugins. JMF, did you have the "Widgets" directory in wp-content/plugins?

or the widgets.php file within /mu-plugins?