Hello, i have the same problem with my wp-installation (not-acceptable-error on the background start-page and when i am trying to create a new category), but your suggestion to set mod_security off does not work on my webserver. I tried zu alter the .htaccess file in both folders, the root folder and the wp-admin folder.
The support of my webserver is totaly incompetent and doesnot even know something about the not-acceptable-problem.
Is there an other possibility to solve it.
