There's a bug in wordpress 2.1 the latest. I have no idea, I just got done publishing a content lastnight and no problem, then today I tried adding a page menu and it added it, but it wont let me write anything. On Firefox it will actually let me write, but after publishing nothing would show. In IE7 I can't type a word. Then another part where I can't add a category anymore. Edit/Delete...Agg! Check this post it seems there are people having the same problem as me, I had a buncha links but I manage to only have two. If any wordpress user 2.1 just letting you know. One day was fine and the next for no reason? http://wordpress.org/support/topic/104590 http://wordpress.org/support/topic/104590
WordPress 2.1.1 was released a few hours ago lest you didn't see. Bug fix release. Might address your issue.