Hmm, this is interesting, I also can’t toggle between “visual” and “code” views. Does that give anyone insight into what may be happening?
Same thing just happened to me, just about to re-install wordpress.
I’m having the same problem, which has appeared out of nowhere on two separate installations of different versions of WP on different servers. Neither have been upgraded/had plugins added or anything similar for a while.
It might well be related to the problems with the editor, which I’ve also had in some installations, and have made numerous support enquiries about, to no avail.
This has just happened to me. I noticed that plain text saved OK, but any attempt to markup caused the save to fail.
May be more than one thing that causes this, but as I noticed that my dashboard was screwed up also, I found the answer at http://wordpress.org/support/topic/117847
I followed the suggestion of whoami (thanks, if you are reading this) and added the .htaccess file to wp-admin.
Solved both problems immediately
