Categories, Tags missing - Need help - self hosted wordpress.org blog

Hi Friends,

I need a help. Suddenly I see that there are missing categories, tags etc., in my new blog which is self hosted on wordpress http://www.techrebels.net .

Please see the screenshot

http://img717.imageshack.us/img717/4357/categoriesmissing.jpg

I'm clueless on why this is happening all of the sudden. When I tried to add new category, tag etc., its not accepting either. There is just one default category called 'Uncategorized'. Please help guys.

Note: I couldn't find any old thread with this issue, so posting new thread, if this is already discussed somewhere, please let me know the link to that thread.