Recently, I upgraded from 2.0.7 to 2.1. When I was using 2.0.7, I could create categories but trying to delete them produced an error in WP which told me I didn't have permission to do that. I was never able to solve that problem.
Now that I've upgraded to 2.1, I can neither delete nor create categories. Attempting to do both results in WP telling me I don't have permission. What could be going wrong here? I'm the admin of my blog and I'm fairly sure all my file permissions are set correctly. Why can't I add new categories?