Undefined variable (across multiple document), upon upgrade

I have over 10 blogs running all with 2.5.1. I followed the instructions for each and made certain to turn off my plug-ins before doing the upgrade.

However, when I started to upgrade the last one, I started to receive errors all over the place (published on the live page and throughout the dashboard).

I have since removed non-default plugins and deactivated those that come with the original install. I attempted to re-install EVERYTHING, with a fresh copy and I still am receiving “undefined variable” errors across the site, such as:

Notice: Undefined variable: toggle in /var/www/vhosts/mix1037fm.com/httpdocs/blog/mixmorning/wp-admin/plugins.php on line 154

Notice: Undefined variable: plugin_info in /var/www/vhosts/mix1037fm.com/httpdocs/blog/mixmorning/wp-admin/plugins.php on line 141

Notice: Undefined index: m in /var/www/vhosts/mix1037fm.com/httpdocs/blog/mixmorning/wp-admin/includes/post.php on line 518

Notice: Undefined index: cat in /var/www/vhosts/mix1037fm.com/httpdocs/blog/mixmorning/wp-admin/includes/post.php on line 519

I just don’t know where to start as a fresh install of wordpress isn’t fixing anything. Is there something wrong with my database?

http://www.mix1037fm.com/blog/mixmorning
Thank you,
k.