I was stuck in this problem too everything is working just cats are vanish and even new added cats are also, in short all the problems was same discussed here by you people.
All I did to solve this problem is that I have reinstall the latest current update of wordpress
I suggest you people that try this with you, may be it will also work with you… just reinstall the current update of word press, don’t deactivate any plugin. And if not works then deactivate all plugins and again reinstall the current update of wordpress.
Good Luck
Regards,
Asif
Surgical Blog
http://www.surgical-blog.com
