Unable to create new categories/new users

I am unable to do the above mentioned tasks within my WP2.1 with K2 theme. I’ve tried all the fixes that I found through searching. I did find someone else who is experiencing the same problem but there were no fixes attached to his post. That is why I decided to open a post of my own.

I only have two plugins that are active/installed. AdSense Deluxe and Akismet. That is all.