erroe 403 when adding new post (after updating)

I had this TERRIBLE idea of updating wp to 3.2.1 today.
The only change I can see so far is that I am no longer allowed to add new posts on my site (www.annozerolive.com).

I can see the site, access the dashboard and perform more or less any other operation BUT I cannot add posts. I compose the post and when I try to preview it, publish it or even save it as draft, I get “error 403 access denied”

I have already done the following:
* checked my ftp credentials (they are alright: 755 for the folders, 644 for the files)
* deactivated all my plugins
* for good measure I renamed the plugins folder on my cpanel and added a new empty plugins folder

Anyone can help? thxx
Angela